CN112417707B - Method for constructing three-dimensional gap model of asphalt mixture - Google Patents
Method for constructing three-dimensional gap model of asphalt mixture Download PDFInfo
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Abstract
The invention discloses a method for constructing a three-dimensional gap model of an asphalt mixture, relates to the field of traffic engineering, and aims to solve the problem that the numerical model of the gap of the existing asphalt mixture cannot accurately reflect the morphological characteristics of the real gap. The invention designs the gap from the two dimensions of the skeleton and the section of the gap respectively; by extracting the gap section of the real asphalt mixture and endowing the gap node, the model construction close to the real gap characteristic can be realized; the void model established by the method is used for simulating the seepage/diffusion/mechanical behavior of the asphalt mixture, and the performance response of the real asphalt pavement can be effectively reflected. The basic design elements of the gap model are the positions of the skeleton nodes and the gap sections, and by controlling the form indexes of the two elements, the design of different characteristic gap models can be realized, and meanwhile, the irregular forms of gaps are considered. The invention is applied to the field of traffic engineering.
Description
Technical Field
The invention relates to the field of traffic engineering, in particular to a characteristic design method of a three-dimensional model of an asphalt mixture gap.
Background
The existence of the gaps in the asphalt mixture provides channels for the transmission and diffusion of moisture/corrosive media and the like, and meanwhile, the uneven distribution of the gaps has obvious influence on the stress transfer mode of the material, so that the characterization of the gap space distribution and the microscopic morphological characteristics is very critical in the research of the mass transfer characteristics and the microscopic mechanical characteristics of the asphalt mixture. With the popularization and application of numerical solving methods such as a finite element method and a discrete element method in the mechanical simulation research of civil engineering materials, the asphalt mixture seepage/diffusion/mechanical numerical simulation based on a digital void model is widely concerned, and the construction of the void model is the basis for developing the research. Due to the lack of evaluation methods for mesoscopic gap characteristics and the consideration of convenient modeling and the like, the construction of the current simulation geometric model adopts a simplified gap model which mainly comprises a stacking ball array model, a capillary tube model, a pipeline model and the like.
However, the simplified gap model ignores the complex morphological characteristics and spatial distribution of the real gap, so that the simulation calculation result is difficult to match with the performance response of the real asphalt pavement, and the solution result has obvious limitation. Therefore, the construction of the asphalt mixture gap model based on the real gap morphological characteristics is the key for improving the reliability of the asphalt mixture numerical value research result. With the popularization and application of nondestructive testing technologies such as industrial CT and the like in the field of civil engineering materials, the detection of the asphalt mixture microscopic gap model becomes possible, and therefore a new method is provided for the digital modeling of the real gap model.
On one hand, however, the asphalt mixture has large void randomness and high variation degree, and the characteristics are difficult to describe; on the other hand, due to the lack of a quantitative evaluation method for complex void forms, the numerical modeling of the voids of the asphalt mixture is difficult to reflect the real void forms, so that the numerical research result of the asphalt mixture cannot accurately represent the working state of the real asphalt pavement. Therefore, it is necessary to establish a method for constructing a void model of an asphalt mixture based on real void morphological characteristics, so as to realize the design and output of the void model with morphological characteristic characterization capability.
The gap model is limited by the asphalt mixture test piece to a great extent, and the diversity of the gap is difficult to describe fully; in addition, the void models are random and irregular, and a plurality of random void models lack corresponding void morphological characteristics and have no contrast. Therefore, the numerical research result of the asphalt mixture cannot accurately represent the working state of the real asphalt pavement. Therefore, it is necessary to establish a method for constructing an asphalt mixture void model based on real void morphological characteristics, so as to realize the design and output of the void model with morphological characteristic characterization capability.
Disclosure of Invention
The invention aims to provide a method for constructing a three-dimensional gap model of an asphalt mixture, aiming at the problem that the numerical model of the gap of the asphalt mixture at present cannot accurately reflect the morphological characteristics of the real gap.
The invention relates to a method for constructing a three-dimensional gap model of an asphalt mixture, which comprises the following steps of:
the method comprises the following steps: void skeleton node determination
Selecting any point in the target gap as an initial gap node according to the design requirement of the target gap, and establishing a space coordinate X, Y, Z of the initial gap node; selecting other gap nodes by taking the initial node as a base point, and establishing a space coordinate X, Y, Z of each gap node; the Z coordinate distances of the other gap nodes are the same; determining the connection relationship between the initial gap node and other gap nodes, and recording the serial number of the gap node connected with the node;
step two: void node profile design
1) Determining a gap section profile control point at the gap height at the gap node position;
2) determining X, Y control point coordinates of the profile of the void section in a planar coordinate system; sequentially inputting the coordinates X, Y of the control points into a csape function of a Matlab platform, calculating to obtain the calculation parameters of a cubic spline curve, inputting the calculation parameters of the cubic spline curve and the number of gap contour points into a ppval function of the Matlab platform, and calculating the coordinate sequence of the gap section contour;
3) assigning the calculated gap section contour coordinate sequence to a gap node;
4) repeating the steps until the section profiles of all the gap nodes are defined;
step three: calculation of a gap skeleton model using a linear similarity gradient algorithm
Regarding the gap nodes and the cross section at the same Z-value height as the same layer, extracting X, Y coordinates of profile points of the gap cross section of the adjacent layer, and if the number of the gap nodes of the adjacent two layers is only one, executing a two-gap linear similarity gradual change algorithm; if two or more than two adjacent layers of gap nodes exist in a certain layer, executing a three-gap linear similarity gradual change algorithm;
the two-gap linear similar gradual change algorithm comprises the following specific steps:
the gaps of two adjacent layers are respectively marked as a gap A and a gap B
5) Calculating centroids of the adjacent two layers of gaps A and B, taking the mean value of coordinates of the profile X, Y as the centroids of the profiles of the gaps, and overlapping the centroids of the two gaps through translation operation;
6) drawing straight lines in the X direction and the Y direction at the centroid position, and dividing the gap contour into four quadrants;
7) respectively extracting control point coordinates corresponding to the gap contour segments in each quadrant, equally dividing the gap contours in the quadrants into 20 parts according to a circumference sharing mode, calculating the coordinates of the division points of the 20 parts of contour segments by adopting a linear interpolation mode, repeating the operation, dividing the contour segments of four quadrants of two gap contours, and recording the coordinates of the division points;
8) dividing points of two layers of gap profile sections in the same quadrant are in one-to-one correspondence, corresponding points are connected, corresponding point connecting lines are equally divided according to the number of interpolation sections between two adjacent layers of gaps, and the step is repeated to equally divide the corresponding point connecting lines in four quadrants;
9) connecting equal division points in the four quadrants correspondingly to form a closed gap profile curve, and calculating to obtain a similar profile curve between two adjacent layers of gaps;
10) translating the gap contour to an original position through reverse translation operation, and calculating a translation distance of the calculated gap contour according to a linear interpolation mode to perform translation operation so that the contour is in a linear gradual change form;
the three-gap linear similar gradient algorithm comprises the following specific steps, wherein a single gap of a certain layer is marked as a gap A, and two gaps of the other layer are respectively marked as a gap B and a gap C;
11) the centroid coordinates of the gap A, the gap B and the gap C are respectively calculated, the centroids of the gap B and the gap C are connected, the centroid connecting line is in the horizontal direction through rotation operation, and the three gap profiles rotate by the same angle;
12) calculating the areas of the gap B and the gap C, and calculating the position of the dividing point P according to the following formula:
in the formula I BP ——O B Distance to point P;
l BC ——O B to O C The distance of (d);
S B -the cross-sectional area of the profile of the void B;
S C -the cross-sectional area of the profile of the void C;
making a straight line in the vertical direction at the point P, and dividing the gap A into two parts, namely a gap A1 and a gap A2;
13) respectively carrying out two-gap linear similarity gradient algorithm by using the gap A1 corresponding to the gap B and the gap A2 corresponding to the gap C, and calculating the gap profile of the middle layer;
14) taking the middle height position of the gap A, at which the gap B and the gap C are similar to gradually change, as a converging position of the intermediate layer gap profile, carrying out fusion operation on the intermediate layer gap profile in adjacent quadrants at the gap A dividing position, wherein the fusion operation specifically comprises the steps of selecting the front 10 points of 20 dividing points for calculating the gap profile in the gap B region, and splicing the front 10 points with the rear 10 points of 20 dividing points for calculating the gap profile in the gap C region to form fused gap profile coordinates, so that the intermediate layer gap profile of the three-gap linear similar gradual change algorithm is obtained through calculation;
step four: deriving design gap tomography images
Extracting the coordinates of the gap contour of any layer, converting the coordinates into a binary image, namely recording matrix points in the gap contour as 0 and recording matrix points outside the gap contour as 1, and outputting the matrix in the form of the binary image;
step five: outputting a gap geometric model by utilizing CT three-dimensional reconstruction software
And (4) importing the void binary image into CT three-dimensional reconstruction software to reconstruct a void model, thereby completing the design of the void model of the asphalt mixture.
The gap contour points in the step two are different from the control points, the control points are only manually determined points with a small number, and the contour points are contour encryption points calculated by adopting a cubic spline curve on the basis.
Furthermore, the number of the void nodes in the step one is 5-20.
Further, the initial gap node space coordinate Z in the step one is 0.
Further, the spatial coordinate Z of the void node described in step one allows repetition.
Furthermore, the number of the contour control points in the second step is 8-16.
Further, the number of the contour coordinate sequences in the step two is 100.
Further, the control point of the void section profile in the second step is a two-dimensional coordinate point determined at the void node height determined in the first step, and is used for controlling the section shape.
Compared with the prior art, the invention has the following advantages:
(1) provides a gap numerical model construction method based on skeleton-section dimension design
The invention divides the gap numerical model construction into two dimensions of the skeleton direction and the section direction of the gap, thereby realizing the simplification of the model construction method, and the specific flow is as follows: firstly, determining the relative space position coordinates of the skeleton nodes (namely the void nodes) of the voids according to the space position trend of the voids, then designing the cross section outline of the voids at the skeleton nodes (namely the void nodes) according to the morphological characteristics of the voids, and finally realizing the calculation of a void model in a three-dimensional space through a corresponding algorithm. By the method, the characterization difficulty of the real gap characteristics is reduced, and the construction of a complex gap model in a three-dimensional space is realized.
(2) Design of gap section by fitting control points with cubic spline curve
The void section of the asphalt mixture has complex shape, large irregularity degree and large section design difficulty. The method comprises the steps of firstly determining the approximate shape of a gap section by using a control point, then obtaining cubic spline curve outline coordinates passing through the control point by using matlab functions csape and ppval with the control point coordinate as a boundary condition, and further designing the shape of the gap section. The method restrains the irregular section shape through the control points, can quickly design the gap contour, and can conveniently modify the gap contour by adjusting the coordinates of the control points.
(3) Provides a method for designing a void model based on the characteristics of a real void
The most basic design parameters of the method for constructing the three-dimensional model of the gap provided by the invention are the space position of a gap skeleton node (namely a gap node) and the profile of a gap section, and the parameters of the two aspects can be obtained in a CT scanning mode, so that a gap numerical model based on the morphological characteristics of the real gap can be established, and the specific implementation mode is as follows: the method comprises the steps of obtaining a tomographic image of a gap of the asphalt mixture through a CT (computed tomography) tomographic scanning technology, extracting a gap skeleton and a section outline of a characteristic node (namely a gap node), and giving the characteristic of the gap skeleton node (namely the gap node) and the section outline to a design model in the design process of the gap model, so that a gap numerical model capable of reflecting the real gap characteristic is established, and the gap characteristic can be adjusted according to research requirements. The method provides a technical means for numerical simulation research under the real gap characteristic.
(4) A linear similarity gradual change algorithm between two/three gaps is provided
The invention provides a linear similarity gradual change algorithm between two/three gaps, and realizes linear transition between the sections of the key gaps of adjacent layers by using a method of corresponding and equidistant division of profile control points of the adjacent gaps. The specific implementation principle is that the equivalent marking of the control points is carried out on the gap sections of the adjacent layers, so that the one-to-one correspondence of the control points of the gap profiles of the adjacent layers is realized; equally dividing the connecting lines of the control points by adopting an equal-interval dividing method; finally, the bisector points are connected, thereby forming an intermediate transition section. By utilizing the algorithm, only the gap profile of the key skeleton node position can be designed, so that the section control profile of each layer of gap can be obtained, and the design workload can be reduced.
The invention has the beneficial effects that:
1) can design complex morphological characteristics or approximate real gap models
The invention adopts a dimension-division design idea to design the gaps from two dimensions of the skeleton and the section of the gaps respectively, and theoretically, the design modeling of any characteristic gap can be realized; by extracting the gap section of the real asphalt mixture and giving a skeleton node, the model construction close to the real gap characteristic can be realized; the void model established by the method is used for simulating the seepage/diffusion/mechanical behavior of the asphalt mixture, and the performance response of the real asphalt pavement can be effectively reflected.
2) Void models can be designed according to target void characteristics
At present, a simplified gap model is mostly adopted for modeling the gap, or three-dimensional reconstruction is carried out by utilizing a CT image. The former is too idealized, ignoring the irregular morphology of the voids; the latter models based on real voids, the void features are limited to CT scan specimens, and the void features are difficult to modify.
Because the basic design elements of the gap model are the positions of the skeleton nodes and the gap sections, the design of the gap models with different characteristics can be realized by controlling the form indexes of the two elements, and meanwhile, the irregular forms of the gaps are considered. The invention provides a way for parameter analysis of the void characteristics of the asphalt mixture, and can realize performance research of the same void model under different void characteristics.
Drawings
FIG. 1 is a diagram of void skeleton nodes and void skeletons;
FIG. 2 is a diagram of void section control points and the resulting profile;
FIG. 3 is a definition diagram of a void section;
FIG. 4 is a graph of a linear similar tapering algorithm between two gaps;
FIG. 5 is a graph of a linear similar gradient algorithm between three gaps;
FIG. 6 is a diagram of a void skeleton model;
FIG. 7 is a view of a void profile and a binarized image;
FIG. 8 is a diagram of a three-dimensional model of a void.
Detailed Description
It will be understood by those of ordinary skill in the art that the foregoing embodiments are specific examples for carrying out the invention, and that various changes in form and details may be made therein without departing from the spirit and scope of the invention in practice.
To make the objects, aspects and advantages of the embodiments of the present invention more apparent, the following detailed description clearly illustrates the spirit of the disclosure, and any person skilled in the art, after understanding the embodiments of the disclosure, may make changes and modifications to the technology taught by the disclosure without departing from the spirit and scope of the disclosure.
The exemplary embodiments of the present invention and the description thereof are provided to explain the present invention and not to limit the present invention.
The following detailed description of embodiments of the invention is provided in connection with the accompanying drawings and the void design examples:
the method comprises the following steps: void skeleton node determination
Selecting any point in the target gap as an initial gap node (gap skeleton node) according to the design requirement of the target gap, and establishing a space coordinate X, Y, Z of the initial gap node (gap skeleton node); selecting other gap nodes by taking the initial node as a base point, and establishing a space coordinate X, Y, Z of each gap node (gap skeleton node); the Z coordinate distances of the other gap nodes are the same; determining the connection relation between the initial gap node (gap skeleton node) and the rest gap nodes (gap skeleton nodes), and recording the serial numbers of the gap nodes (gap skeleton nodes) connected with the initial gap node (gap skeleton node);
the main design parameters of the void nodes (void skeleton nodes) are shown in table 1, and the void nodes (void skeleton nodes) are shown in fig. 1.
TABLE 1 design parameters for void skeleton nodes
Step two: void node profile design
1) Determining a gap section profile control point at the gap height at the position of a gap node (gap skeleton node); according to the complexity of the cross section, the number of contour control points is usually preferably 8-16, as shown in the control points in FIG. 2, and the coordinates of the control points are shown in Table 2;
2) determining X, Y control point coordinates of the profile of the void section in a planar coordinate system; sequentially inputting the coordinates X, Y of the control points into a csape function of a Matlab platform, calculating to obtain the calculation parameters of a cubic spline curve, inputting the calculation parameters of the cubic spline curve and the number of gap contour points into a ppval function of the Matlab platform, and calculating the coordinate sequence of the gap section contour; see fig. 2 for a cross-section; the number of the contour coordinates can be determined as required, in order to ensure the accuracy of the gap section and simultaneously consider the calculation cost of the gap model, 40-100 contour points are preferably used, and the sequence of the contour points is shown in a table 3;
3) assigning the calculated gap section contour coordinate sequence to a gap node;
4) repeating the steps until the section profiles of all the gap nodes are defined; the definition of the void section at each node is shown in FIG. 3;
TABLE 2 design coordinates of control points for gap sections
| Serial number | X coordinate | Y coordinate | Serial number | X coordinate | Y coordinate |
| 1 | 2 | 2 | 6 | 8 | 5 |
| 2 | 3 | 3 | 7 | 10 | 3 |
| 3 | 3 | 5 | 8 | 8 | 1 |
| 4 | 5 | 8 | 9 | 6 | 2 |
| 5 | 7 | 7 | 10 | 4 | 1 |
TABLE 3 void section Profile calculation coordinates
Step three: calculation of a gap skeleton model using a linear similarity gradient algorithm
Regarding the gap nodes and the cross section at the same Z-value height as the same layer, extracting X, Y coordinates of gap cross section contour points of the adjacent layer, and if the number of the gap contour points of the two adjacent layers is only one, executing a two-gap linear similarity gradual change algorithm; if two or more than two layers of gap contour points exist in the two adjacent layers of gap contour points, a three-gap linear similarity gradual change algorithm is executed;
the two-gap linear similarity gradual change algorithm specifically comprises the following steps, and the adjacent two layers of gaps are respectively marked as a gap A and a gap B, as shown in figure 4.
1) Calculating centroids of the adjacent two layers of gaps A and B, taking the mean value of coordinates of the contour X, Y as the centroid of the contour of the gap, and coinciding the centroids of the two gaps through translation operation;
2) drawing straight lines in the X direction and the Y direction at the centroid position, and dividing the gap contour into four quadrants;
3) and respectively extracting control point coordinates corresponding to the gap profile sections in each quadrant, equally dividing the gap profiles in the quadrants into 20 parts according to a perimeter-sharing mode, and calculating the coordinates of the division points of the 20 parts of profile sections by adopting a linear interpolation mode. The operation is repeated, the contour segments of four quadrants of the two clearance contours are divided, and the coordinates of the dividing points are recorded.
4) And (3) carrying out one-to-one correspondence on the division points of the two layers of gap profile sections in the same quadrant, connecting the corresponding points, and equally dividing the connecting lines of the corresponding points according to the number of the interpolation sections between the two adjacent layers of gaps. Repeating the step to equally divide the corresponding point connecting lines in the four quadrants;
5) and connecting the bisector points in the four quadrants correspondingly to form a closed gap contour curve, and calculating to obtain a similar contour curve between two adjacent layers of gaps.
6) And translating the gap contour to an original position through reverse translation operation, and calculating a translation distance of the calculated gap contour according to a linear interpolation mode to perform translation operation so that the contour is in a linear gradual change form.
The three-gap linear similarity gradient algorithm comprises the following specific steps, wherein a single gap of one layer is marked as a gap A, and two gaps of the other layer are respectively marked as a gap B and a gap C, and the three-gap linear similarity gradient algorithm is shown in the attached figure 5.
1) And respectively calculating the centroid coordinates of the gap A, the gap B and the gap C, connecting the centroids of the gap B and the gap C, and rotating to enable the centroid connecting line to be in the horizontal direction, wherein the three gap profiles rotate by the same angle.
2) Calculating the areas of the gap B and the gap C, and calculating the position of the dividing point P according to the following formula:
in the formula I BP ——O B Distance to point P;
l BC ——O B to O C The distance of (d);
S B -the cross-sectional area of the profile of the void B;
S C -the cross-sectional area of the profile of the void C.
Making a straight line in the vertical direction at the point P, and dividing the gap A into two parts, namely a gap A1 and a gap A2;
3) and respectively carrying out two-gap linear similarity gradient algorithm by using the gap A1 corresponding to the gap B and the gap A2 corresponding to the gap C, and calculating the gap profile of the middle layer.
4) And taking the middle height position of the gap A, which is gradually changed towards the gap B and the gap C, as the merging position of the intermediate layer gap profile, and fusing the intermediate layer gap profile in the adjacent quadrant at the gap A segmentation position, wherein the fusing operation specifically comprises the steps of selecting the front 10 points of 20 segmentation points of the calculated gap profile in the gap B region and splicing the front 10 points with the rear 10 points of the 20 segmentation points of the calculated gap profile in the gap C region to form the fused gap profile coordinates. And calculating to obtain the intermediate layer gap profile of the three-gap linear similarity gradient algorithm.
The gap skeleton model obtained by calculation of the similar gradient algorithm is shown in figure 6.
Step four: deriving design gap tomography images
And (3) extracting the coordinates of the gap contour of any layer, converting the coordinates into a binary image, namely recording matrix points in the gap contour as 0 and recording matrix points outside the gap contour as 1, and outputting the matrix in the form of the binary image, wherein the contour of the gap and the binary image are shown in an attached figure 7.
Step five: outputting a gap geometric model by utilizing CT three-dimensional reconstruction software
And (3) importing the void binary image into CT three-dimensional reconstruction software, reconstructing a void model, and outputting a three-dimensional model which can be used for numerical simulation calculation, as shown in figure 8. Thus, the design of the asphalt mixture gap model is completed.
Claims (7)
1. A method for constructing a three-dimensional gap model of an asphalt mixture is characterized by comprising the following steps of:
the method comprises the following steps: void skeleton node determination
Selecting any point in the target gap as an initial gap node according to the design requirement of the target gap, and establishing a space coordinate X, Y, Z of the initial gap node; selecting other gap nodes by taking the initial node as a base point, and establishing a space coordinate X, Y, Z of each gap node; the Z coordinate intervals of the other gap nodes are the same; determining the connection relationship between the initial gap node and other gap nodes, and recording the serial number of the gap node connected with the node;
step two: void node profile design
1) Determining a gap section profile control point at the gap height at the gap node position;
2) determining X, Y control point coordinates of the profile of the void section in a planar coordinate system; sequentially inputting the control point coordinates X, Y into a Matlab platform csape function, calculating to obtain the calculation parameters of a cubic spline curve, inputting the calculation parameters of the cubic spline curve and the number of gap contour points into a Matlab platform ppval function, and calculating the coordinate sequence of the gap section contour;
3) assigning the calculated gap section contour coordinate sequence to a gap node;
4) repeating the steps until the section profiles of all the gap nodes are defined;
step three: calculation of a gap skeleton model using a linear similarity gradient algorithm
Regarding the gap nodes and the cross section at the same Z-value height as the same layer, extracting X, Y coordinates of profile points of the gap cross section of the adjacent layer, and if the number of the gap nodes of the adjacent two layers is only one, executing a two-gap linear similarity gradual change algorithm; if two or more than two adjacent layers of gap nodes exist in a certain layer, executing a three-gap linear similarity gradual change algorithm;
the two-gap linear similar gradual change algorithm comprises the following specific steps:
the gaps of two adjacent layers are respectively marked as a gap A and a gap B
5) Calculating centroids of the adjacent two layers of gaps A and B, taking the mean value of coordinates of the profile X, Y as the centroids of the profiles of the gaps, and overlapping the centroids of the two gaps through translation operation;
6) drawing straight lines in the X direction and the Y direction at the centroid position, and dividing the gap contour into four quadrants;
7) respectively extracting control point coordinates corresponding to the gap contour segments in each quadrant, equally dividing the gap contours in the quadrants into 20 parts according to a circumference sharing mode, calculating the coordinates of the division points of the 20 parts of contour segments by adopting a linear interpolation mode, repeating the operation, dividing the contour segments of four quadrants of two gap contours, and recording the coordinates of the division points;
8) dividing points of two layers of gap profile sections in the same quadrant are in one-to-one correspondence, corresponding points are connected, corresponding point connecting lines are equally divided according to the number of interpolation sections between two adjacent layers of gaps, and the step is repeated to equally divide the corresponding point connecting lines in four quadrants;
9) connecting equal division points in the four quadrants correspondingly to form a closed clearance contour curve, and calculating to obtain a similar contour curve between two adjacent layers of clearances;
10) translating the gap contour to an original position through reverse translation operation, and calculating a translation distance of the calculated gap contour according to a linear interpolation mode to perform translation operation so that the contour is in a linear gradual change form;
the three-gap linear similar gradient algorithm comprises the following specific steps, wherein a single gap of a certain layer is marked as a gap A, and two gaps of the other layer are respectively marked as a gap B and a gap C;
11) the centroid coordinates of the gap A, the gap B and the gap C are respectively calculated, the centroids of the gap B and the gap C are connected, the centroid connecting line is in the horizontal direction through rotation operation, and the three gap profiles rotate by the same angle;
12) calculating the areas of the gap B and the gap C, and calculating the position of the dividing point P according to the following formula:
in the formula I BP ——O B Distance to point P;
l BC ——O B to O C The distance of (a);
S B -the cross-sectional area of the profile of the void B;
S C -the cross-sectional area of the profile of the void C;
making a straight line in the vertical direction at the point P, and dividing the gap A into two parts, namely a gap A1 and a gap A2;
13) respectively carrying out two-gap linear similarity gradient algorithm by using the gap A1 corresponding to the gap B and the gap A2 corresponding to the gap C, and calculating the gap profile of the middle layer;
14) taking the middle height position of the gap A, at which the gap B and the gap C are similar to gradually change, as a converging position of the intermediate layer gap profile, carrying out fusion operation on the intermediate layer gap profile in adjacent quadrants at the gap A dividing position, wherein the fusion operation specifically comprises the steps of selecting the front 10 points of 20 dividing points for calculating the gap profile in the gap B region, and splicing the front 10 points with the rear 10 points of 20 dividing points for calculating the gap profile in the gap C region to form fused gap profile coordinates, so that the intermediate layer gap profile of the three-gap linear similar gradual change algorithm is obtained through calculation;
step four: deriving design gap tomography images
Extracting the coordinates of the gap contour of any layer, converting the coordinates into a binary image, namely recording matrix points in the gap contour as 0 and recording matrix points outside the gap contour as 1, and outputting the matrix in the form of the binary image;
step five: outputting a gap geometric model by utilizing CT three-dimensional reconstruction software
And (4) importing the void binary image into CT three-dimensional reconstruction software to reconstruct a void model, thereby completing the design of the void model of the asphalt mixture.
2. The method for constructing the three-dimensional void model of the bituminous mixture according to claim 1, wherein the number of void nodes in step one is 5-20.
3. The method for constructing the three-dimensional void model of asphalt mixture according to claim 1, wherein the initial void node space coordinate Z in the first step is 0.
4. The method for constructing the three-dimensional void model of asphalt mixture as claimed in claim 1, wherein the spatial coordinates Z of the void nodes in step one are allowed to be repeated.
5. The method for constructing the three-dimensional void model of the asphalt mixture according to claim 1, wherein the number of the contour control points in the second step is 8-16.
6. The method for constructing the three-dimensional void model of asphalt mixture according to claim 1, wherein the number of the contour coordinate sequences in the second step is 100.
7. The method for constructing the three-dimensional void model of asphalt mixture as claimed in claim 1, wherein the control points of the void section profile in the second step are two-dimensional coordinate points determined at the height of the void node determined in the first step, for controlling the section shape.
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