Two-dimensional concrete numerical model random generation method based on aggregate characteristics

Abstract

The invention discloses a two-dimensional concrete numerical model random generation method based on aggregate characteristics, relates to the technical field of concrete materials, and solves the problems that in the prior art, a random distribution mode is single, and the complexity and randomness of spatial distribution of aggregate in actual concrete cannot be fully simulated. The randomness and the comprehensiveness of aggregate characteristics still need to be improved. The method comprises the following steps: determining a two-dimensional target area and area of aggregate feeding; determining the two-dimensional gradation of the aggregate based on a Fuller gradation curve and a varagen formula; calculating a theoretical value of each graded aggregate area according to the area of the target region; when the random aggregate geometric model is generated, circular, elliptical and polygonal aggregates in different shapes are randomly generated according to a descending order of grading, and meanwhile, the geometric model of the random aggregate is finally generated by judging the position relationship among the aggregates and avoiding the overlapping phenomenon, so that the problem is solved.

Description

Technical Field

[0001] The invention belongs to the field of concrete materials, and in particular relates to a random generation method of a two-dimensional concrete numerical model based on aggregate characteristics. Background Art

[0002] As a widely used building material, the properties of concrete directly affect the safety and durability of the structure. The microstructure and aggregate characteristics of concrete have a crucial impact on these properties. Traditional models usually use aggregates of regular shapes, such as spheres or ellipses, but these models cannot fully capture the complexity of actual concrete, especially the randomness in the shape, size distribution and spatial arrangement of aggregates. The microstructure of concrete may change due to many factors. In recent years, with the development of computer technology, numerical simulation methods have been widely used in the study of ultrasonic testing of concrete. Researchers have tried to simulate concrete aggregates through random generation methods in order to more accurately reflect the microstructure of concrete in two-dimensional numerical models. These methods can simulate the internal heterogeneity and anisotropy of concrete through randomly distributed aggregates and pores, thus providing a new perspective for the study of the mechanical properties and durability of concrete.

[0003] In the field of ultrasonic or phased array ultrasonic testing simulation of concrete, although some studies have attempted to capture the randomness and complexity of concrete through numerical simulation, the existing methods have a single random distribution pattern and fail to fully simulate the complexity and randomness of the spatial distribution of aggregates in actual concrete. In addition, the overlapping processing method is simple, which may cause the generated model to be unnatural. In addition, the existing methods are also limited in the comprehensiveness of aggregate characteristics, such as single shape, limited grading range and simple spatial arrangement. They fail to fully cover all particle size ranges and complex spatial arrangements that may appear in actual concrete. Therefore, the existing methods still need to be improved in terms of randomness and comprehensiveness of aggregate characteristics.

[0004] Therefore, the present invention proposes a random generation method of a two-dimensional concrete numerical model based on aggregate characteristics to solve the above problems. Summary of the invention

[0005] The present invention aims to solve at least one of the technical problems existing in the prior art; to this end, the present invention proposes a random generation method for a two-dimensional concrete numerical model based on aggregate characteristics, which is used to solve the problem that the existing method has a single random distribution pattern and fails to fully simulate the complexity and randomness of the spatial distribution of aggregates in actual concrete, and the overlapping processing method is simple, which may cause the generated model to be unnatural. In addition, the existing method also has limitations in the comprehensiveness of aggregate characteristics, such as a single shape, a limited gradation range, and a simple spatial arrangement, which fails to fully cover all particle size ranges and complex spatial arrangements that may appear in actual concrete. Therefore, the existing method still has technical problems in terms of randomness and the comprehensiveness of aggregate characteristics that need to be improved.

[0006] To achieve the above object, a first aspect of the present invention provides a method for randomly generating a two-dimensional concrete numerical model based on aggregate characteristics, comprising:

[0007] Step 1: Determine the two-dimensional target area for aggregate placement and the area of ​​the two-dimensional target area;

[0008] Step 2: Determine the two-dimensional grading of aggregate;

[0009] Step 3: Based on the area of ​​the two-dimensional target area, the theoretical value of the area of ​​each level of aggregate is calculated;

[0010] Step 4: Generate the geometric model of random aggregate that meets the two-dimensional grading requirements step by step in the order of gradation from large to small.

[0011] Preferably, the determining of the two-dimensional target area for aggregate placement and the area of ​​the two-dimensional target area comprises:

[0012] A1: Use the preset shape as the boundary of the 2D target area;

[0013] A2: Extract the dimensions of the preset shape;

[0014] A3: The area of ​​the two-dimensional target region is calculated based on the size of the preset shape.

[0015] It should be noted that the two-dimensional target area refers to a specific plane area where the aggregate is placed or simulated; the preset shape is set according to actual work requirements, and the preset shapes include: circle, rectangle, polygon, etc.; the area of ​​the target area calculated based on the size of the preset shape refers to using an appropriate area calculation formula (such as the area formula of a circle πr 2 , the area formula of a rectangle (length × width, etc.) is used to calculate the area of ​​the target area.

[0016] Preferably, the determining of the two-dimensional gradation of aggregate comprises:

[0017] The mass percentage of aggregates with different particle sizes was calculated through the Fuller gradation curve;

[0018] The expression of Fuller gradation curve is:

[0019]

[0020] Where P(d) is the mass percentage of aggregate passing through the sieve hole d; d is the sieve hole diameter; D max is the maximum aggregate particle size; n is the equation index, and the value range of n is between 0.45 and 0.7;

[0021] The probability of aggregates with different graded distribution appearing in the two-dimensional target area is calculated by Walravin formula, which is used as the two-dimensional gradation of aggregates.

[0022] The Walaven formula is:

[0023]

[0024] Among them, P k is the percentage of aggregate (including coarse aggregate and fine aggregate) in the total volume of concrete, D0 is the upper limit of the diameter of each level of aggregate, P c is the probability that each level of aggregate appears on the two-dimensional plane, that is, the area fraction of each level of aggregate in the total area of ​​the placement area.

[0025] It should be noted that the Fuller gradation curve is a method for optimizing aggregate gradation, which aims to achieve the best filling effect between aggregates, reduce the void ratio, and improve the density and strength of concrete. The Fuller gradation curve is used to determine the mass distribution of aggregates with different particle sizes. Specifically, the Fuller gradation curve can help understand the maximum particle size D max The mass percentage of aggregates in each particle size range under ;

[0026] The Walravin formula is a formula that converts the three-dimensional aggregate grading curve into the probability of occurrence of aggregates of any diameter in a two-dimensional plane. It enables the distribution of aggregates to be accurately simulated in two-dimensional numerical simulations. The Walravin formula is used to calculate the probability of occurrence of each grade of aggregate in a two-dimensional plane. This step is to convert the mass distribution into a spatial distribution and ensure that the distribution of the generated aggregate model in a two-dimensional plane meets the grading requirements of actual concrete.

[0027] Preferably, the area calculation based on the two-dimensional target area to obtain the theoretical value of the area of ​​each level of aggregate includes:

[0028] The area of ​​the two-dimensional target region is marked as S;

[0029] By formula: LS c =P c ×S, calculate the theoretical value of the area of ​​each level of aggregate; where LSc is the theoretical value of the area of ​​aggregate at each level, P c is the probability of each level of aggregate appearing on the two-dimensional plane.

[0030] By calculating the theoretical value of the area of ​​each level of aggregate, the area of ​​each level of aggregate in the geometric model of the generated random aggregate can be determined.

[0031] Preferably, the stepwise grading generates a geometric model of random aggregates that meets the two-dimensional grading requirements, including:

[0032] S1: Generate random aggregate shapes based on two-dimensional grading requirements; wherein the random aggregate shapes include: circle, ellipse and polygon;

[0033] S2: Record the geometric data of random aggregate shapes; the geometric data are randomly generated using the Math.random random number function in COMSOL Multiphysics, and each aggregate shape does not intersect the boundary of the two-dimensional target area; the geometric data include: the center coordinates and radius of circular aggregates; the ellipse center coordinates, major semi-axis, minor semi-axis and inclination angle of elliptical aggregates; the polygon center coordinates, circumscribed circle radius, number of sides and angle of sides of polygonal aggregates;

[0034] S3: Determine the positional relationship of the circles generated in S1;

[0035] The judgment condition is: when the distance between the centers of two circles is less than the sum of their radii, the positions of the two circles are determined to overlap, the circle generated later in the sequence is deleted, and the circle generated earlier is retained;

[0036] S4: Determine the positional relationship of the ellipses generated in S1;

[0037] The judgment condition is: when the distance between the center points of two ellipses is less than the sum of the lengths of the major and minor semi-axes of the two ellipses, the positions of the two ellipses are determined to overlap, the ellipse generated later in the sequence is deleted, and the ellipse generated earlier is retained;

[0038] S5: Determine the positional relationship of the polygons generated in S1;

[0039] The judgment condition is: when the center distance between two polygons is less than the sum of their radii, the positions of the two polygons are determined to overlap, the polygon generated later in the sequence is deleted, and the polygon generated earlier is retained;

[0040] S6: placing aggregates of different grade according to the judgment conditions of the position relationship in steps S3-S5 until the total area of ​​the generated aggregate shapes exceeds the theoretical value of the total aggregate area, i.e., stopping the cycle;

[0041] S7: repeating steps S1-S6 until all graded aggregate geometric models are generated; wherein the aggregate geometric models include: a geometric model of a circular aggregate, a geometric model of an elliptical aggregate, and a geometric model of a polygonal aggregate.

[0042] It should be noted that the two-dimensional grading requirement means that on a two-dimensional plane, aggregates of different particle sizes are combined according to a certain proportion and distribution pattern to meet specific grading requirements; the two-dimensional grading requirements include: the two-dimensional target area for placing aggregates, the area ratio of each level of aggregate, the mass distribution of aggregates of different particle sizes and the spatial distribution of aggregates of different particle sizes; among them, the area ratio of each level of aggregate means that in the generated aggregate model, the area of ​​each level of aggregate should be consistent with the theoretical value ratio of the calculated area.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] 1. The existing methods have a single random distribution pattern and fail to fully simulate the complexity and randomness of the spatial distribution of aggregates in actual concrete. In addition, the overlapping processing method is simple, which may cause the generated model to be unnatural. In addition, the existing methods also have limitations in the comprehensiveness of aggregate characteristics, such as single shape, limited gradation range and simple spatial arrangement, which fail to fully cover all particle size ranges and complex spatial arrangements that may appear in actual concrete. Therefore, the existing methods still have technical problems to be improved in terms of randomness and comprehensiveness of aggregate characteristics; the present invention determines the two-dimensional target area and area for aggregate placement, and then determines the two-dimensional gradation of aggregate based on the Fuller gradation curve and the Walravin formula, and then calculates the theoretical value of the area of ​​each level of aggregate according to the area of ​​the target area; when generating a random aggregate geometric model, according to the order of gradation from large to small, COMSOL Multiphysics software is used to randomly generate aggregates of different shapes such as circles, ellipses and polygons, and record their geometric data. At the same time, by judging the positional relationship between aggregates, the occurrence of overlapping phenomena is avoided until the total area of ​​the generated aggregate shapes exceeds the theoretical value of the total aggregate area; the present invention simulates the complexity and randomness of the spatial distribution of aggregates in actual concrete, and the aggregates have diverse shapes and a wide gradation range, which fully covers all particle size ranges and complex spatial arrangements that may appear in actual concrete, thereby improving the accuracy and naturalness of the model.

[0045] 2. The present invention utilizes the built-in Java function of COMSOL Multiphysics, which effectively reduces the dependence on complex algorithms and reduces the complexity of programming. At the same time, the generated aggregate distribution can be visualized in two dimensions in COMSOL software, making the simulation process more intuitive and efficient.

[0046] 3. The present invention controls the shape of polygonal aggregate by means of polygonal circumscribed circles without changing its equivalent particle size. This method can more realistically simulate the geometric characteristics of polygonal aggregate while maintaining the aggregate size distribution, thereby enhancing the practical application value of the model. 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 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.

[0048] Figure 1 A schematic diagram of the method steps of an embodiment of the present invention;

[0049] Figure 2 A schematic diagram of generating a geometric model of random aggregate according to an embodiment of the present invention;

[0050] Figure 3 Schematic diagram of the geometric model for generating circular, elliptical and polygonal aggregates in an embodiment of the present invention. DETAILED DESCRIPTION

[0051] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than 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.

[0052] See also Figure 1 The first embodiment of the present invention provides a method for randomly generating a two-dimensional concrete numerical model based on aggregate characteristics, comprising:

[0053] Step 1: Determine the two-dimensional target area for aggregate placement and the area of ​​the two-dimensional target area;

[0054] Step 2: Determine the two-dimensional grading of aggregate;

[0055] Step 3: Based on the area of ​​the two-dimensional target area, the theoretical value of the area of ​​each level of aggregate is calculated;

[0056] Step 4: Generate the geometric model of random aggregate that meets the two-dimensional grading requirements step by step in the order of gradation from large to small.

[0057] Determine the two-dimensional target area for aggregate placement and the area of ​​the two-dimensional target area, including:

[0058] A1: Use the preset shape as the boundary of the 2D target area;

[0059] A2: Extract the dimensions of the preset shape;

[0060] A3: The area of ​​the two-dimensional target region is calculated based on the size of the preset shape.

[0061] Determine the two-dimensional gradation of aggregates, including:

[0062] The mass percentage of aggregates with different particle sizes was calculated through the Fuller gradation curve;

[0063] The expression of Fuller gradation curve is:

[0064]

[0065] Where P(d) is the mass percentage of aggregate passing through the sieve hole d; d is the sieve hole diameter; D max is the maximum aggregate particle size; n is the equation index, and the value range of n is between 0.45 and 0.7;

[0066] The probability of aggregates with different graded distribution appearing in the two-dimensional target area is calculated by Walravin formula, which is used as the two-dimensional gradation of aggregates.

[0067] The Walaven formula is:

[0068]

[0069] Among them, P k is the percentage of aggregate (including coarse aggregate and fine aggregate) in the total volume of concrete, D0 is the upper limit of the diameter of each level of aggregate, P c is the probability that each level of aggregate appears on the two-dimensional plane, that is, the area fraction of each level of aggregate in the total area of ​​the placement area.

[0070] The theoretical values ​​of the aggregate areas at each level are calculated based on the area of ​​the two-dimensional target area, including:

[0071] The area of ​​the two-dimensional target region is marked as S;

[0072] By formula: LS c =P c ×S, calculate the theoretical value of the area of ​​each level of aggregate; where LS c is the theoretical value of the area of ​​aggregate at each level, P c is the probability of each level of aggregate appearing on the two-dimensional plane.

[0073] See also Figure 2 , the geometric model of random aggregate that meets the two-dimensional grading requirements is generated step by step, including:

[0074] S1: Generate random aggregate shapes based on two-dimensional grading requirements; wherein the random aggregate shapes include: circle, ellipse and polygon;

[0075] S2: Record the geometric data of random aggregate shapes; the geometric data are randomly generated using COMSOL Multiphysics, and each aggregate shape does not intersect the boundary of the two-dimensional target area; the geometric data include: the center coordinates and radius of circular aggregates; the ellipse center coordinates, major semi-axis, minor semi-axis and inclination angle of elliptical aggregates; the polygon center coordinates, circumscribed circle radius, number of sides and angle of sides of polygonal aggregates;

[0076] S3: Determine the positional relationship of the circles generated in S1;

[0077] The judgment condition is: when the distance between the centers of two circles is less than the sum of their radii, the positions of the two circles are determined to overlap, the circle generated later in the sequence is deleted, and the circle generated earlier is retained;

[0078] S4: Determine the positional relationship of the ellipses generated in S1;

[0079] The judgment condition is: when the distance between the center points of two ellipses is less than the sum of the lengths of the major and minor semi-axes of the two ellipses, the positions of the two ellipses are determined to overlap, the ellipse generated later in the sequence is deleted, and the ellipse generated earlier is retained;

[0080] S5: Determine the positional relationship of the polygons generated in S1;

[0081] The judgment condition is: when the center distance between two polygons is less than the sum of their radii, the positions of the two polygons are determined to overlap, the polygon generated later in the sequence is deleted, and the polygon generated earlier is retained;

[0082] S6: placing aggregates of different grade according to the judgment conditions of the position relationship in steps S3-S5 until the total area of ​​the generated aggregate shapes exceeds the theoretical value of the total aggregate area, i.e., stopping the cycle;

[0083] S7: repeating steps S1-S6 until all graded aggregate geometric models are generated; wherein the aggregate geometric models include: a geometric model of a circular aggregate, a geometric model of an elliptical aggregate, and a geometric model of a polygonal aggregate.

[0084] For example: Step 1: determine the two-dimensional target area for aggregate placement and the area of ​​the two-dimensional target area;

[0085] Assume that the target delivery area is a rectangle with a height of 300 mm and a width of 400 mm. The target area is 120,000 mm. 2 .

[0086] Step 2: Determine the two-dimensional grading of aggregate;

[0087] In this embodiment, the selected grading scheme is a two-stage grading, with aggregate particle sizes of 5-20mm and 20-40mm. The ratio of the two aggregate particle sizes is 5.5:4.5 to construct different aggregate shapes. Aggregates with a particle size below 5mm are regarded as cement mortar matrix and no aggregate generation is performed.

[0088] The mass percentage of aggregates with different particle sizes was calculated through the Fuller gradation curve;

[0089] The expression of Fuller gradation curve is:

[0090]

[0091] Where P(d) is the mass percentage of aggregate passing through the sieve hole d; d is the sieve hole diameter; D max is the maximum aggregate particle size; n is the equation index, and the value range of n is between 0.45 and 0.7;

[0092] The probability of aggregates with different graded distribution appearing in the two-dimensional target area is calculated by Walravin formula, which is used as the two-dimensional gradation of aggregates.

[0093] The Walaven formula is:

[0094]

[0095] Among them, P k is the percentage of aggregate (including coarse aggregate and fine aggregate) in the total volume of concrete, D0 is the upper limit of the diameter of each level of aggregate, P c is the probability that each level of aggregate appears on the two-dimensional plane, that is, the area fraction of each level of aggregate in the total area of ​​the placement area.

[0096] Step 3: Based on the area of ​​the two-dimensional target area, the theoretical value of the area of ​​each level of aggregate is calculated;

[0097] The area of ​​the two-dimensional target region is marked as S;

[0098] By formula: LS c =P c ×S, calculate the theoretical value of the area of ​​each level of aggregate; where LS c is the theoretical value of the area of ​​aggregate at each level, P c is the probability of each level of aggregate appearing on the two-dimensional plane.

[0099] Step 4: Generate the geometric model of random aggregate that meets the two-dimensional grading requirements step by step in the order of gradation from large to small.

[0100] S1: Generate random aggregate shapes based on two-dimensional grading requirements; wherein the random aggregate shapes include: circle, ellipse and polygon;

[0101] S2: Record the geometric data of random aggregate shapes; the geometric data are randomly generated using COMSOL Multiphysics, and each aggregate shape does not intersect the boundary of the two-dimensional target area; the geometric data include: the center coordinates and radius of circular aggregates; the ellipse center coordinates, major semi-axis, minor semi-axis and inclination angle of elliptical aggregates; the polygon center coordinates, circumscribed circle radius and number of sides of polygonal aggregates;

[0102] S3: Determine the positional relationship of the circles generated in S1;

[0103] In this embodiment, the aggregate placement area is a rectangle of 300 mm × 400 mm. Generate random circles with a particle size within the range of the secondary aggregate, and use the built-in Math.random() random number function of COMSOL Multiphysics to generate random numbers for aggregate size and position, including the coordinates of the center of the circle and the radius, and ensure that each circular aggregate does not intersect the boundary of the placement area.

[0104] The radius of the circular aggregate is represented by r, and its size is between 2.5-20 mm. In COMSOL, a random number algorithm is used to generate two sets of random numbers as the horizontal and vertical coordinates of the center of the circle. To prevent the circular aggregate from intersecting the boundary of the target area, the distance between the horizontal and vertical coordinates of the center of the circle and the boundary should be greater than the radius of the circle.

[0105] Determine the positional relationship of the generated random circles. The determination method is: when the distance between the centers of two circles is less than the sum of the radii, the positions of the two circles are determined to overlap, the circle generated later in the sequence is deleted, and the circle generated earlier is retained.

[0106] Suppose the radius of one circle is r1, and the coordinates of its center are (x1, y1); the radius of another circle is r2, and the coordinates of its center are (x2, y2). , determine that the two do not overlap, otherwise, delete the generated circle.

[0107] S4: Determine the positional relationship of the ellipses generated in S1;

[0108] In this embodiment, the aggregate placement area is a rectangle of 300 mm × 400 mm. Generate a random ellipse with a particle size within the range of the secondary aggregate, and use the built-in Math.random() random number function of COMSOL Multiphysics to generate random numbers for aggregate size and position, including the ellipse center coordinates, major semi-axis, minor semi-axis and inclination angle, and ensure that each elliptical aggregate does not intersect with the boundary of the placement area.

[0109] The major semi-axis of the elliptical aggregate is represented by a, and the minor semi-axis is represented by b. The sizes of the major semi-axis and the minor semi-axis are both between 2.5 and 20 mm. A random number algorithm is used in COMSOL to generate two sets of random numbers as the horizontal and vertical coordinates of the center of the ellipse. To prevent the elliptical aggregate from intersecting the boundary of the target area, the distance between the horizontal and vertical coordinates of the center of the ellipse and the boundary should be greater than the major semi-axis of the ellipse.

[0110] The positional relationship of the generated random ellipses is determined as follows: when the distance between the center points of two ellipses is less than the sum of the lengths of their major and minor semi-axes, the positions of the two ellipses are determined to overlap, the ellipse generated later in the sequence is deleted, and the ellipse generated earlier is retained.

[0111] Suppose that the major axis of one ellipse is a1, the minor axis is b1, and the coordinates of the center of the ellipse are (x3, y3); the major axis of the other ellipse is a2, the minor axis is b2, and the coordinates of the center of the ellipse are (x4, y4). , it is determined that the two do not overlap, otherwise, the resulting ellipse is deleted.

[0112] S5: Determine the positional relationship of the polygons generated in S1;

[0113] In this embodiment, the aggregate placement area is a rectangle of 300 mm×400 mm. Generate a random polygon with a particle size within the range of the secondary aggregate, and use the built-in double function of COMSOL Multiphysics to define the minimum radius and maximum radius of the random polygon circumscribed circle, with a radius range of [3, 8].

[0114] Use the int function to define the number of sides of a random polygon, determine the minimum and maximum number of sides, and the range of the number of sides is [5, 10].

[0115] The Math.random() random number function is used to generate random numbers for the size and position of polygonal aggregates, including the polygon center coordinates, circumscribed circle radius, number of edges and edge angles, and to ensure that each polygonal aggregate does not intersect the boundary of the placement area.

[0116] The radius of the polygonal aggregate is represented by rd, and its size is between 2.5-20 mm. Using the random number algorithm in COMSOL, two sets of random numbers are generated as the horizontal and vertical coordinates of the polygon center. To prevent the polygonal aggregate from intersecting with the boundary of the target area, the distance between the horizontal and vertical coordinates of the polygon center and the boundary should be greater than the radius of the circumscribed circle of the polygon.

[0117] The positional relationship of the generated random polygons is determined as follows: when the center distance between two polygons is less than the sum of the radii of the circumscribed circles of the two polygons, the positions of the two polygons are determined to overlap, the polygon generated later in the sequence is deleted, and the polygon generated earlier is retained.

[0118] Finally, we use the COMSOL Multiphysics API to create polygons, set their vertex coordinates and run the geometry build.

[0119] S6: placing aggregates of different grade according to the judgment conditions of the position relationship in steps S3-S5 until the total area of ​​the generated aggregate shapes exceeds the theoretical value of the total aggregate area, i.e., stopping the cycle;

[0120] S7: repeating steps S1-S6 until all graded aggregate geometric models are generated; wherein the aggregate geometric models include: a geometric model of a circular aggregate, a geometric model of an elliptical aggregate, and a geometric model of a polygonal aggregate.

[0121] See also Figure 3 , using COMSOL Multiphysics API for geometry construction.

[0122] Part of the data in the above formula is calculated by removing the dimension and taking its numerical value. The formula is a formula closest to the actual situation obtained by software simulation of a large amount of collected data; the preset parameters and preset thresholds in the formula are set by technical personnel in this field according to actual conditions or obtained through simulation of a large amount of data.

[0123] The above embodiments are only used to illustrate the technical method of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical method of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical method of the present invention.

Claims

1. A random generation method of a two-dimensional concrete numerical model based on aggregate characteristics, characterized in that: include: Step 1: Determine the two-dimensional target area for aggregate placement and the area of ​​the two-dimensional target area; Step 2: Determine the two-dimensional grading of aggregate; Step 3: Based on the area of ​​the two-dimensional target area, the theoretical value of the area of ​​each level of aggregate is calculated; Step 4: Generate the geometric model of random aggregate that meets the two-dimensional grading requirements step by step in the order of gradation from large to small.

2. The random generation method of a two-dimensional concrete numerical model based on aggregate characteristics according to claim 1 is characterized in that: The step of determining the two-dimensional target area for aggregate placement and the area of ​​the two-dimensional target area comprises: A1: Use the preset shape as the boundary of the 2D target area; A2: Extract the dimensions of the preset shape; A3: The area of ​​the two-dimensional target region is calculated based on the size of the preset shape.

3. The random generation method of a two-dimensional concrete numerical model based on aggregate characteristics according to claim 1 is characterized in that: Determining the two-dimensional gradation of aggregates comprises: The mass percentage of aggregates with different particle sizes was calculated through the Fuller gradation curve; The expression of Fuller gradation curve is: Where P(d) is the mass percentage of aggregate passing through the sieve hole d; d is the sieve hole diameter; D max is the maximum aggregate particle size; n is the equation index, and the value range of n is between 0.45 and 0.7; The probability of aggregates with different graded distribution appearing in the two-dimensional target area is calculated by Walravin formula, which is used as the two-dimensional gradation of aggregates. The Walaven formula is: Among them, P k is the percentage of aggregate in the total volume of concrete, D0 is the upper limit of the diameter of each level of aggregate, P c is the probability that each level of aggregate appears on the two-dimensional plane, that is, the area fraction of each level of aggregate in the total area of ​​the placement area.

4. The random generation method of a two-dimensional concrete numerical model based on aggregate characteristics according to claim 1 is characterized in that: The theoretical values ​​of the areas of various aggregates at various levels are obtained by calculating the area of ​​the two-dimensional target area, including: The area of ​​the two-dimensional target region is marked as S; By formula: LS c =P c ×S, calculate the theoretical value of the area of ​​each level of aggregate; where LS c is the theoretical value of the area of ​​aggregate at each level, P c is the probability of each level of aggregate appearing on the two-dimensional plane.

5. The random generation method of a two-dimensional concrete numerical model based on aggregate characteristics according to claim 1 is characterized in that: The step-by-step grading method generates a geometric model of random aggregates that meets the two-dimensional grading requirements, including: S1: Generate random aggregate shapes based on two-dimensional grading requirements; wherein the random aggregate shapes include: circle, ellipse and polygon; S2: Record the geometric data of random aggregate shapes; the geometric data are randomly generated using the Math.random random number function in COMSOL Multiphysics, and each aggregate shape does not intersect the boundary of the two-dimensional target area; the geometric data include: the center coordinates and radius of circular aggregates; the ellipse center coordinates, major semi-axis, minor semi-axis and inclination angle of elliptical aggregates; the polygon center coordinates, circumscribed circle radius, number of sides and angle of sides of polygonal aggregates; S3: Determine the positional relationship of the circles generated in S1; The judgment condition is: when the distance between the centers of two circles is less than the sum of their radii, the positions of the two circles are determined to overlap, the circle generated later in the sequence is deleted, and the circle generated earlier is retained; S4: Determine the positional relationship of the ellipses generated in S1; The judgment condition is: when the distance between the center points of two ellipses is less than the sum of the lengths of the major and minor semi-axes of the two ellipses, the positions of the two ellipses are determined to overlap, the ellipse generated later in the sequence is deleted, and the ellipse generated earlier is retained; S5: Determine the positional relationship of the polygons generated in S1; The judgment condition is: when the center distance between two polygons is less than the sum of their radii, the positions of the two polygons are determined to overlap, the polygon generated later in the sequence is deleted, and the polygon generated earlier is retained; S6: placing aggregates of different grade according to the judgment conditions of the position relationship in steps S3-S5 until the total area of ​​the generated aggregate shapes exceeds the theoretical value of the total aggregate area, i.e., stopping the cycle; S7: Repeat steps S1-S6 until the geometric models of all graded aggregates are generated.

6. The random generation method of a two-dimensional concrete numerical model based on aggregate characteristics according to claim 5 is characterized in that: The aggregate geometric model includes: a geometric model of a circular aggregate, a geometric model of an elliptical aggregate and a geometric model of a polygonal aggregate.

Images