Two-dimensional microscopic performance analysis method for reinforced concrete segment structures of shield tunnels

Abstract

The present invention relates to a two-dimensional microscopic performance analysis method for a reinforced concrete segment structure of a shield tunnel, and the method comprises: S1, determining internal boundary parameters; S2, determining external boundary parameters; S3, determining the shape and size of two-dimensional aggregates; S4, establishing external boundaries and internal boundaries; S5, placing aggregates according to an aggregate random position algorithm, judging whether the area fraction of the aggregates after placing matches the target area fraction, if so, executing S6, otherwise returning to S3; S6, generating spatial positions for aggregates based on a spatial grid-aggregate matching strategy; S7, repeating S5 and S6 to obtain a two-dimensional microscopic elliptical-circular aggregate model of the segment; S8, extracting contour feature points, generating concave-convex aggregates, and obtaining a two-dimensional microscopic structural model of a real segment. The present invention realizes a microscopic modeling method of heterogeneous segment materials for the first time, improves the accuracy and efficiency of segment fine modeling and cracking damage assessment, and has the advantages of universal applicability.

Description

Technical Field

[0001] The invention relates to the technical field of shield tunnel segment materials and structure simulation, and in particular to a two-dimensional microscopic performance analysis method for a shield tunnel reinforced concrete segment structure. Background Art

[0002] Shield tunneling is the main construction method for major projects such as river-crossing tunnels and subway tunnels in my country. The common cross-section of shield tunnels is a circular tunnel. The segments, as the permanent lining structure of the shield tunnel, are mainly prefabricated with reinforced concrete, including several standard blocks (B), two adjacent blocks (L) and a capping block (F).

[0003] In shield tunnel construction projects, high-performance concrete with strength grade C50 or above is often used for segment concrete. The superior compressive strength of C50 or above concrete reduces the tensile strength and has high brittleness. Therefore, tunnel segments are prone to cracks under building loads. Segment cracking not only directly weakens the durability of the lining and destroys the integrity of the lining structure, but also leads to subsequent problems such as tunnel leakage and steel corrosion. Therefore, establishing a real mesoscopic model of the segment structure and clarifying the mesoscopic mechanism of segment cracking are difficult issues that need to be paid attention to and solved in the new stage of tunnel engineering development.

[0004] The traditional design method of tunnel segment structure often regards the reinforced concrete segment as a whole for full-scale test analysis of bearing capacity. Given the limitations of mechanical tests, the test is not only costly but also difficult to accurately measure the mesoscopic damage state of the segment. The numerical models established in existing work are also macroscopic and homogeneous models. For example, the "homogeneous ring model" and "beam-spring model" of the tunnel segment lateral internal force calculation model both equate the segment lining as a homogeneous ring with the same cross-sectional stiffness to a certain extent. Due to the limitations of macroscopic homogeneous model analysis and assumptions, the heterogeneity of the material composition of the reinforced concrete segment itself is ignored, which directly leads to the low accuracy of the mesoscopic damage analysis of the segment structure. At present, more and more studies have pointed out that the mesoscopic structural characteristics of the material will dominate the mechanical behavior of the structure, and the reinforced concrete segment can be regarded as composed of three phases of aggregate, mortar and steel at the mesoscopic level. From the perspective of building materials, it can be seen that heterogeneous multiphase composite materials have complex mesoscopic structural characteristics, and their mechanical properties and fracture properties are also significantly different due to differences in material composition. For example, circular aggregates in concrete can average structural stress, while polygonal aggregates have stress concentration effects. In view of the complexity of the stress characteristics of the arc-shaped shield tunnel segment itself and the shortcomings of experiments and macro and homogeneous models in the analysis of segment damage and cracking, there is currently a lack of refined modeling and analysis methods that consider the mesoscopic properties of materials in the modeling of reinforced concrete segments of shield tunnels. Summary of the invention

[0005] The purpose of the present invention is to overcome the defects of the above-mentioned prior art and to provide a two-dimensional micro-performance analysis method for the reinforced concrete segment structure of a shield tunnel.

[0006] The purpose of the present invention can be achieved by the following technical solutions:

[0007] A two-dimensional microscopic performance analysis method for reinforced concrete segment structures of shield tunnels, including:

[0008] S1. Determine the segmentation form, segment diameter and thickness of the shield tunnel;

[0009] S2. Determine the type and laying form of the circumferential reinforcement of the tunnel segments;

[0010] S3. Determine the shape and size of the two-dimensional aggregate of each grading section in the segment structure according to the grading curve;

[0011] S4. Establish the outer boundary of the two-dimensional mesoscopic model of the segment according to the segment block form, segment diameter and thickness of the shield tunnel segment of S1, and establish the inner boundary of the two-dimensional mesoscopic model according to the type and laying form of the annular reinforcement of the tunnel segment of S2;

[0012] S5, according to the target gradation, according to the aggregate random position algorithm, put the aggregate of a gradation section determined by S3, and judge whether the area fraction of the aggregate of the gradation section in the two-dimensional micro-model after putting it matches the area fraction of the aggregate in the target model. If so, execute S6, otherwise return to S3 to re-determine the shape and size of the two-dimensional aggregate of the gradation section;

[0013] S6. generating a suitable spatial position for the aggregate based on a spatial grid-aggregate matching strategy, wherein the spatial position satisfies the boundary requirements;

[0014] Repeat S5 and S6 until all aggregates are placed, and obtain a two-dimensional mesoscopic elliptical-circular aggregate model of the standard block of the reinforced concrete segment;

[0015] S7, repeat S5 and S6 until all aggregates are placed, and obtain a two-dimensional mesoscopic elliptical-circular aggregate model of a standard reinforced concrete segment block;

[0016] S8. Extract the original contour feature points of the aggregate, generate two-dimensional meso-concave-convex aggregate, and analyze the meso-structural characteristics and structural meso-mechanical properties of the segment structure based on the two-dimensional meso-concave-convex aggregate.

[0017] Furthermore, the aggregate of S3 is a circular two-dimensional aggregate with different ovality generated according to the grading curve. i+1 The corresponding grading curve of aggregate with sieve size [d i , d i+1] segment, the particle size of this group of aggregates corresponds to the equivalent diameter d of the two-dimensional elliptical aggregate e Satisfy e =2r2 and r2≥r1 and 2r2≤d i+1 , where r i (i=1,2) is the main radius of the ellipse.

[0018] Furthermore, the equivalent diameter of the two-dimensional elliptical aggregate is:

[0019]

[0020] Among them, X is a random number uniformly distributed from 0 to 1, d i represents the size of the sieve hole i, d i+1 Represents the size of sieve hole i+1.

[0021] Furthermore, the calculation process of the area fraction of aggregate in the grading section in the two-dimensional mesoscopic model is:

[0022] For the grading section [d i , d i+1 The area of ​​any two-dimensional aggregate i in ] is s i =π×r1×r2, gradation section [d i , d i+1 The total area of ​​a group of aggregates in ] is S i+1 =∑s i+1 , the structural size S of aggregate in the two-dimensional microscopic model s The total area occupied by c =∑S i+1 , we can get the area fraction P of the aggregate in the gradation segment in the two-dimensional microscopic model c for:

[0023]

[0024] Among them, r i (i=1,2) is the main radius of the ellipse, and the grading section [d i , d i+1 ] corresponds to d i+1 Aggregate with sieve size.

[0025] Furthermore, based on the aggregate random position algorithm, during the process of placing aggregates in the graded section, the aggregates are translated and rotated to truly simulate the posture and spatial position of the aggregates.

[0026] Furthermore, when the aggregate is placed, the initial position matrix of the aggregate is The final position E of the aggregate is: Among them, the initialization position matrix for:

[0027]

[0028] Among them, r i (i=1,2) is the main radius of the ellipse;

[0029] The translation matrix D of the aggregate spatial position is:

[0030]

[0031] Among them, (c x ,c y ) is the coordinate of the aggregate center;

[0032] The rotation matrix R of the aggregate spatial position is:

[0033]

[0034] Where θ is the rotation angle, θ∈(0, 2π), c θ = cosθ, s θ = sinθ.

[0035] Furthermore, when placing aggregates, they are placed in sequence from the grading section with the largest aggregate particle size to the grading section with the smaller aggregate particle size according to the target gradation.

[0036] Furthermore, meeting the boundary requirements specifically means that the gaps between aggregates, between aggregates and external boundaries, and between aggregates and internal boundaries are used to fill mortar, and the aggregates are located within the external boundary, and the aggregates do not penetrate the internal boundary or the external boundary.

[0037] Furthermore, the area within the outer boundary is discretized into incompatible rectangular areas. When the aggregate is placed, it is placed in the specified rectangular area to automatically meet the boundary requirements. The rectangular area C is expressed as:

[0038]

[0039] Among them, (c x ,c y ) is the coordinate of the aggregate center; l x and l y Respectively represent the length and width of the rectangle, [] represents rounding, (x, y) represents the coordinates of the rectangle, N x The number of rectangular regions on the x-axis representing the area within the outer boundary, N y The number of rectangular areas on the y-axis representing the area within the outer boundary, N x and N y The total number of aggregates already placed in the grading section and the total number of aggregates placed in the current grading section N e Related.

[0040] Furthermore, the concave-convex aggregate is generated by setting a random length of the main radius of the ellipse of the aggregate and extracting a coordinate sequence of feature points of the original contour part of the ellipse aggregate.

[0041] Compared with the prior art, the present invention has the following advantages:

[0042] The present invention truly considers multiple types of boundary conditions in the circular arc reinforced concrete segments of the tunnel, ensures that the spatial position of the aggregate meets the boundary requirements, and simulates the irregular shape, posture and spatial position characteristics of the real aggregate according to the aggregate random position algorithm, realizing the heterogeneous micro-analysis modeling method of the segment material for the first time. At the same time, the "spatial grid-aggregate" matching strategy greatly weakens the "traversal" judgment of the boundary incompatibility conditions between aggregates, improves the efficiency of the segment micro-modeling, has the characteristics of authenticity and efficiency, is suitable for universal promotion and application, and can better analyze the micro-structural characteristics and structural micro-mechanical properties of the segment. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 is a flow chart of the present invention;

[0044] Figure 2 This is a schematic diagram of the shield tunnel segment division;

[0045] Figure 3 is a schematic diagram of random aggregate and its translation and rotation;

[0046] Figure 4 It is a schematic diagram of the inner and outer boundaries of the two-dimensional model of reinforced concrete segments;

[0047] Figure 5 Schematic diagram of the two-dimensional mesoscopic elliptical-circular aggregate model of the standard block of reinforced concrete segment;

[0048] Figure 6 Simplified schematic diagram of the characteristic points of the aggregate profile;

[0049] Figure 7 It is a schematic diagram of the two-dimensional mesoscopic concave-convex aggregate model of the standard block of reinforced concrete segment;

[0050] In the figure: 1—outer boundary of reinforced concrete segment; 2—mortar-aggregate filling area of ​​reinforced concrete segment; 3—inner steel bars of reinforced concrete segment; 4—circular aggregate; 5—elliptical aggregate; 6—mortar filling area; 7—concave-convex aggregate; 8—convex elliptical aggregate; 9—convex polygonal aggregate. DETAILED DESCRIPTION

[0051] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0052] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. 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.

[0053] Example 1

[0054] The present invention proposes a two-dimensional microscopic performance analysis method for a reinforced concrete segment structure of a shield tunnel. The flowchart of the method is as follows: Figure 1 The method comprises the following steps:

[0055] S1. Determine the segmentation form, segment diameter and thickness of the shield tunnel;

[0056] S2. Determine the type and laying form of the circumferential reinforcement of the tunnel segments;

[0057] S3. Determine the shape and size of the two-dimensional aggregate of each grading section in the segment structure according to the grading curve;

[0058] S4. Establish the outer boundary of the two-dimensional mesoscopic model of the segment according to the segment block form, segment diameter and thickness of the shield tunnel segment of S1, and establish the inner boundary of the two-dimensional mesoscopic model according to the type and laying form of the annular reinforcement of the tunnel segment of S2;

[0059] S5, according to the target gradation, according to the aggregate random position algorithm, put the aggregate of a gradation section determined by S3, and judge whether the area fraction of the aggregate of the gradation section in the two-dimensional micro-model after putting it matches the area fraction of the aggregate in the target model. If so, execute S6, otherwise return to S3 to re-determine the shape and size of the two-dimensional aggregate of the gradation section;

[0060] S6, generating appropriate spatial positions for aggregates based on spatial grid-aggregate matching strategy, where the spatial positions meet boundary requirements;

[0061] S7, repeat S5 and S6 until all aggregates are placed, and obtain a two-dimensional mesoscopic elliptical-circular aggregate model of a standard reinforced concrete segment block;

[0062] S8. Extract the original contour feature points of the aggregate, generate two-dimensional meso-concave-convex aggregate, and analyze the meso-structural characteristics and structural meso-mechanical properties of the segment structure based on the two-dimensional meso-concave-convex aggregate.

[0063] In S1, the block structure of the tunnel full ring segments is composed of 4 to 8 pieces according to the tunnel diameter and the lifting capacity of the assembly machinery. The full ring of the subway tunnel is usually composed of 6 pieces (3B+2L+L) or 7 pieces (4B+2L+L) of segments. The block structure mainly affects the angle and size of the segments.

[0064] The diameter of the segment is divided into inner diameter and outer diameter, which is generally related to the size of the shield machine. At present, the outer diameter of the largest tunnel segment in China can reach 16.8m. The thickness of the segment ranges from 0.04 to 0.06D (D is the outer diameter of the tunnel), and the commonly used thickness is 300 to 500mm.

[0065] In S2, the type and laying form of steel bars in the two-dimensional tunnel microscopic model mainly consider the diameter and layer position of the annular steel bars. Because the annular steel bars in the two-dimensional structure of a circular tunnel mainly enhance the bearing capacity of the segments, their laying forms mainly include single-layer steel bars and double-layer steel bars.

[0066] In S3, the Fuller gradation curve or the actual production gradation curve can obtain an aggregate numerical model that is consistent with the statistical distribution characteristics of the actual aggregate size. The shape of the two-dimensional aggregate in the segment structure is determined by generating circular two-dimensional aggregates of different ovality according to the gradation curve. The shape expression of the elliptical aggregate is:

[0067]

[0068] Among them, r i (i=1,2) is the main radius of the ellipse. The radius r1 of the two-dimensional ellipse aggregate can be expressed by the radius r2 as:

[0069]

[0070] m is the shape parameter of elliptical aggregate. The larger m is, the flatter the aggregate is. When m=1, r1=r2, the elliptical aggregate degenerates into circular aggregate.

[0071] According to the principle of graded screening of aggregate particle size, i+1 The corresponding grading curve of aggregate with sieve size [d i , d i+1 ] segment, according to "probability statistics" and "inversion", the target grading segment [d i , d i+1 ] corresponds to the two-dimensional elliptical aggregate equivalent diameter of the aggregate particle size group:

[0072]

[0073] X is a random number uniformly distributed from 0 to 1; therefore, in d e =2r2 and r2≥r1, when the diameter of the elliptical aggregate is 2r2≤d i+1 It is considered that the aggregate passes through the diameter d i+1 Finally, all the i+1 The aggregate composition gradation curve of the size sieve hole [d i , d i+1 ] segment.

[0074] In S4, the internal and external boundary parameters of the shield tunnel segment 2D structure model are determined based on the actual external and internal structure of the tunnel reinforced concrete segment. Figure 4 As shown, the outer boundary 1 of the reinforced concrete segment, the mortar-aggregate filling area 2 of the reinforced concrete segment and the internal steel bars 3 of the reinforced concrete segment are determined.

[0075] In S5, the aggregate is translated and rotated by the aggregate random position algorithm to simulate the posture and spatial position of the aggregate; the spatial position and posture direction of any elliptical aggregate can be expressed by the matrix x T Ex=0 describes the initialization position matrix where the center of the aggregate is at the origin and the radius is aligned with the coordinate axis. for:

[0076]

[0077] The translation matrix D of the aggregate spatial position is:

[0078]

[0079] The rotation matrix R of the aggregate spatial position is:

[0080]

[0081] The final position E of the aggregate can be expressed as Finally, according to the target gradation, the aggregate is placed in order from the gradation section with the largest aggregate size to the gradation section with the smallest aggregate size. i ,y i ,1] T , x i ,y i is the aggregate boundary; (c x ,c y ) is the coordinate of the aggregate center, c x 、c y c x =min(x)+(max(x)-min(x))×X, c y =min(y)+(max(y)-min(y))×X; θ is the rotation angle, θ∈(0, 2π), cθ = cosθ, s θ = sinθ

[0082] For the grading section [d i , d i+1 The area s of any two-dimensional aggregate i in i =π×r1×r2, gradation section [d i , d i+1 The total area S of a group of aggregates in i+1 =∑s i+1 , aggregate in structural size S s The total area occupied by c =∑S i+1 .according to:

[0083]

[0084] The area fraction P of aggregate in the structure can be calculated c , and then judge P c Whether the area fraction P of aggregate in the target structure is met s , that is, P c and P s If they are equal, then execute S6, otherwise return to S3 to redefine the shape and size of the two-dimensional aggregate of the grading section.

[0085] In S6, in order to ensure that the aggregate is completely wrapped by mortar and the aggregate does not penetrate the boundaries of the steel bars and the pipe segments, the "spatial grid-aggregate" matching strategy is adopted to automatically meet various boundary incompatibility conditions, weaken the judgment of the "traversal" of the boundaries of the aggregate, steel mesh and pipe segments by the boundary incompatibility conditions between boundaries, and improve the modeling efficiency. According to the incompatibility criterion, the boundaries of the aggregate, steel mesh and pipe segments are judged to be filled with mortar between the aggregates, the aggregate-pipe segment boundaries and the aggregate-steel boundaries in the reinforced concrete pipe segment, and the aggregate is located inside the boundary of the pipe segment structure, and the aggregate cannot penetrate the boundaries of the steel bars and pipe segments. Due to the large number of aggregates in the reinforced concrete pipe segment, the efficiency of boundary incompatibility judgment between the aggregates and between the aggregates and various boundaries is low. In order to improve the modeling efficiency, the present invention discretizes the aggregate-mortar area of ​​the reinforced concrete pipe segment into incompatible rectangular areas. The process of placing the aggregates into the specified rectangular area automatically meets various boundary incompatibility conditions, which greatly improves the efficiency of boundary incompatibility judgment.

[0086] As the aggregate placing process continues, the corresponding number of segments N generated by placing aggregates into the aggregate-mortar area i Continuously increase, the number of spatial grid segments N for aggregate placement i N is the total number of aggregates put into the grading section e The function is:

[0087]

[0088] Among them, l x and l y is the size of the rectangular area. In order to automatically meet the boundary incompatibility condition in any aggregate placement process, the “spatial grid-aggregate” matching strategy expands the aggregate placement rectangular area by ε times to ensure that the aggregate is wrapped by the mortar filling area. The expanded elliptical aggregate radius R i =(1+ε)×r i , i = 1, 2; from the coordinates of the aggregate center (c x ,c y ) indicates that the corresponding space grid rectangle C is:

[0089]

[0090] Among them, [] means rounding, and mini means finding the minimum coordinates of the rectangular border.

[0091] In order to ensure that any aggregate placement process automatically satisfies the boundary incompatibility condition, the aggregate placement rectangle can be enlarged by ε times, and the enlarged space can automatically satisfy the boundary incompatibility condition.

[0092] In S7, S5 and S6 are repeated until all graded sections [d i , d i+1 ] are placed in groups of aggregates, and the random distribution positions and postures of all elliptical aggregates of different shapes and sizes in the segment are obtained.

[0093] In S8, a two-dimensional microscopic concave-convex aggregate simulating the geometric characteristics of real aggregates is generated. The two-dimensional microscopic concave-convex aggregate is a concave-convex aggregate with real aggregate geometric characteristics formed by simplifying the original contour feature points of elliptical aggregates of different shapes and sizes in S7 in combination with the mathematical and statistical characteristics of aggregate shapes.

[0094] According to the statistical characteristics of aggregate, the convex aggregate is composed of the original contour feature points (x i ,y i ) is drawn by extracting the coordinate sequence of the original contour feature points of the elliptical aggregate in clockwise or counterclockwise direction at the initial point; the concave and convex aggregate is drawn by setting the major and minor axes of the aggregate r 1i , r 2i The random length is drawn by extracting the coordinate sequence of the feature points of the original contour of the elliptical aggregate in a clockwise or counterclockwise direction. The coordinate of the center of the aggregate (x e ,y e ), aggregate rotation angle θ; the contour feature point extraction formula is as follows:

[0095] x i =r 1i cos(θ)cos(α i )-r2i sin(θ)sin(α i )+x e

[0096] y i =r 1i cos(θ)sin(α i )-r 2i sin(θ)cos(α i )+y e

[0097] The radius of the i-th contour feature point

[0098] The radius of the starting point is R1=r1, and the central angle is:

[0099]

[0100] The radius of the i-th vertex (i is a positive integer) angle:

[0101]

[0102] n is the number of sides of the aggregate, X i A random number in the specified interval.

[0103] The concave and convex aggregate with real aggregate geometric characteristics can fix the coordinates of the aggregate center (x e ,y e ), by setting the random length interval of the major and minor axes r1, r2 of the aggregate, extracting the coordinate sequence of the original contour feature points of the elliptical aggregate in a clockwise or counterclockwise direction, and drawing all the contour feature points (x i ,y i ) coordinates to obtain a closed two-dimensional concave-convex aggregate.

[0104] Taking a flat plate segment as an example, the present invention is further described below in conjunction with the accompanying drawings and embodiments:

[0105] The entire ring of a subway tunnel is usually composed of 6 (3B+2L+L) or 7 (4B+2L+L) segments. Since the actual stress state of the segments will change with different stages of the project, the segment design is usually divided into blocks. Figure 2 The standard block (B) in the figure is described in detail.

[0106] S1. According to the segment block form, segment diameter and thickness of the shield tunnel, the segment structure is determined: the outer radius is 3000mm, the inner radius is 2700mm, the width is 1200mm, and the center angle is 67.5°. The concrete strength grade is C50;

[0107] S2. Determine the type and laying form of the segment's circumferential reinforcement. The upper row of main reinforcement is φ18mm, and the lower row of main reinforcement is φ18mm. The upper row of main reinforcement is 59mm away from the upper edge of the segment, the lower row of main reinforcement is 43mm away from the lower edge of the segment, and the reinforcement is 51mm away from the edges of both ends of the segment;

[0108] S3. In the embodiment, the grading mainly uses two grades of aggregates, with a maximum aggregate size of 30 mm, an intermediate aggregate size of 22.5 mm, and a minimum aggregate size of 15 mm; the aggregate area fraction is 0.6, and the shape factor m=1.5. The two-dimensional aggregate in the segment structure is generated according to the grading curve. Figure 3 As shown;

[0109] S4. According to the external and internal structure of the tunnel segment, the inner and outer boundaries of the shield tunnel segment two-dimensional structure model are determined by S1 and S2. Figure 4 As shown, the outer boundary 1 of the reinforced concrete segment, the mortar-aggregate filling area 2 of the reinforced concrete segment and the internal reinforcement 3 of the reinforced concrete segment are clearly defined;

[0110] S5. Place aggregates according to the target gradation. According to the random position algorithm of aggregates, aggregates can be randomly translated and rotated without overlapping each other. The schematic diagram of random aggregate placement is shown in Figure 3 ;

[0111] S6. The “spatial grid-aggregate” matching strategy can generate appropriate spatial locations for aggregates, including the coordinates of the aggregate center (x e ,y e ), rotation angle θ; the process of placing aggregates into the grid can automatically meet various boundary incompatibility conditions and ensure that the aggregates are completely wrapped by mortar and the boundaries between the aggregates and the steel bars and segments do not penetrate. The process of random aggregate placement into the grid is as follows Figure 3 As shown;

[0112] S7, repeat the above steps of S5 to S6, and after all the aggregates are placed, a two-dimensional microscopic elliptical-circular aggregate model of the standard block of reinforced concrete segment that meets the boundary requirements is obtained as follows Figure 5 As shown, circular aggregate 4, elliptical aggregate 5 and mortar filling area 6 are obtained;

[0113] S8. After determining the center coordinates and major and minor axes of each elliptical-circular aggregate, a schematic diagram of a concave-convex aggregate with real aggregate geometric characteristics is constructed by simplifying the characteristic points of the aggregate. Figure 6 , Figure 6 -(a) is a schematic diagram of convex polygonal aggregate, Figure 6 -(b) is a schematic diagram of circular concave and convex aggregates. Figure 6-(c) is a schematic diagram of an elliptical concave-convex aggregate. In the embodiment, according to the statistical characteristics of the aggregate, the number of extracted contour feature points n is set to a range of 10 to 18 and obeys a logarithmic normal distribution; the random factor X of the major and minor axes is i belongs to 0.8~1.1 and is uniformly distributed; the two-dimensional microscopic concave-convex aggregate simulating the geometric characteristics of the real aggregate is obtained. Figure 7 As shown, concave-convex aggregate 7, convex elliptical aggregate 8 and convex polygonal aggregate 9 can be obtained.

[0114] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A two-dimensional microscopic performance analysis method for reinforced concrete segment structures of shield tunnels, characterized in that: include: S1. Determine the segmentation form, segment diameter and thickness of the shield tunnel; S2. Determine the type and laying form of the circumferential reinforcement of the tunnel segments; S3. Determine the shape and size of the two-dimensional aggregate of each grading section in the segment structure according to the grading curve; S4. Establish the outer boundary of the two-dimensional mesoscopic model of the segment according to the segment block form, segment diameter and thickness of the shield tunnel segment of S1, and establish the inner boundary of the two-dimensional mesoscopic model according to the type and laying form of the annular reinforcement of the tunnel segment of S2; S5, according to the target gradation, according to the aggregate random position algorithm, put the aggregate of a gradation section determined by S3, and judge whether the area fraction of the aggregate of the gradation section in the two-dimensional micro-model after putting it matches the area fraction of the aggregate in the target model. If so, execute S6, otherwise return to S3 to re-determine the shape and size of the two-dimensional aggregate of the gradation section; S6. generating a suitable spatial position for the aggregate based on a spatial grid-aggregate matching strategy, wherein the spatial position satisfies the boundary requirements; S7, repeat S5 and S6 until all aggregates are placed, and obtain a two-dimensional mesoscopic elliptical-circular aggregate model of a standard reinforced concrete segment block; S8, extracting the original contour feature points of the aggregate, generating two-dimensional micro-concave-convex aggregates, and analyzing the micro-structural characteristics and structural micro-mechanical properties of the segment structure based on the two-dimensional micro-concave-convex aggregates; Among them, the irregular shape, posture and spatial position characteristics of real aggregates are simulated according to the aggregate random position algorithm; The spatial grid-aggregate matching strategy automatically satisfies various boundary incompatibility conditions; Meeting the boundary requirements specifically means that there are gaps between aggregates, between aggregates and external boundaries, and between aggregates and internal boundaries for filling mortar, and the aggregates are located within the external boundary, and the aggregates do not penetrate the internal boundary or the external boundary.

2. The two-dimensional microscopic performance analysis method of the reinforced concrete segment structure of a shield tunnel according to claim 1 is characterized in that: The aggregate of S3 is a two-dimensional circular aggregate with different ovality generated according to the grading curve. i+1 The corresponding grading curve of aggregate with sieve size [d i , d i+1 ] segment, the particle size of this group of aggregates corresponds to the equivalent diameter d of the two-dimensional elliptical aggregate e Satisfy e =2r2 and r2>r1, and 2r2≤d i+1 , where r i (i=1,2) is the main radius of the ellipse.

3. The two-dimensional microscopic performance analysis method of the reinforced concrete segment structure of a shield tunnel according to claim 2 is characterized in that: The equivalent diameter of a two-dimensional elliptical aggregate is: Among them, X is a random number uniformly distributed from 0 to 1, d i represents the size of the sieve hole i, d i+1 Represents the size of sieve hole i+1.

4. The two-dimensional microscopic performance analysis method of the reinforced concrete segment structure of a shield tunnel according to claim 1 is characterized in that: The calculation process of the area fraction of aggregate in the gradation section in the two-dimensional mesoscopic model is: For the grading section [d i , d i+1 The area of ​​any two-dimensional aggregate i in ] is s i =π×r1×r2, gradation section [d i , d i+1 The total area of ​​a group of aggregates in ] is S i+1 =∑s i+1 , the structural size S of aggregate in the two-dimensional microscopic model s The total area occupied by c =∑S i+1 , we can get the area fraction P of the aggregate in the gradation segment in the two-dimensional microscopic model c for: Among them, r i (i=1,2) is the main radius of the ellipse, and the grading section [d i , d i+1 ] corresponds to d i+1 Aggregate with sieve size.

5. The two-dimensional microscopic performance analysis method of the reinforced concrete segment structure of a shield tunnel according to claim 1 is characterized in that: Based on the random position algorithm of aggregates, during the process of placing aggregates in the graded section, the aggregates are translated and rotated to truly simulate the posture and spatial position of the aggregates.

6. The two-dimensional microscopic performance analysis method of the reinforced concrete segment structure of a shield tunnel according to claim 5 is characterized in that: When the aggregate is placed, the initial position matrix of the aggregate is The final position E of the aggregate is: Among them, the initialization position matrix for: Among them, r i (i=1,2) is the main radius of the ellipse; The translation matrix D of the aggregate spatial position is: Among them, (c x ,c y ) is the coordinate of the aggregate center; The rotation matrix R of the aggregate spatial position is: Where θ is the rotation angle, θ∈(0, 2π), c θ = cosθ, s θ = sinθ.

7. The two-dimensional microscopic performance analysis method of the reinforced concrete segment structure of a shield tunnel according to claim 6 is characterized in that: When placing aggregates, place them in order from the grading section with the largest aggregate particle size to the grading section with smaller aggregate particle size according to the target gradation.

8. The two-dimensional microscopic performance analysis method of the reinforced concrete segment structure of a shield tunnel according to claim 1 is characterized in that: The area within the external boundary is discretized into incompatible rectangular areas. When the aggregate is placed, it is placed in the specified rectangular area to automatically meet the boundary requirements. The rectangular area C is expressed as: Among them, (c x ,c y ) is the coordinate of the aggregate center; l x and l y Respectively represent the length and width of the rectangle, [] represents rounding, (x, y) represents the coordinates of the rectangle, N x The number of rectangular regions on the x-axis representing the area within the outer boundary, N y The number of rectangular areas on the y-axis representing the area within the outer boundary, N x and N y The total number of aggregates already placed in the grading section and the total number of aggregates placed in the current grading section N e Related.

9. The two-dimensional microscopic performance analysis method of the reinforced concrete segment structure of a shield tunnel according to claim 1 is characterized in that: The concave-convex aggregate is generated by setting the random length of the main radius of the ellipse of the aggregate and extracting the coordinate sequence of the feature points of the original contour part of the ellipse aggregate.

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