CN115618702B - Method for generating two-dimensional ultrahigh volume fraction mixed rock numerical simulation model by adopting overlapping contact cutting algorithm - Google Patents
Method for generating two-dimensional ultrahigh volume fraction mixed rock numerical simulation model by adopting overlapping contact cutting algorithm Download PDFInfo
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Abstract
The invention discloses a method for generating a two-dimensional ultra-high volume fraction mixed rock numerical simulation model by adopting an overlapped contact cutting algorithm, which comprises the steps of randomly generating a polygonal aggregate frame according to preconditions such as a given grain grading curve; recording coordinate information of a polygonal aggregate frame, introducing discrete meta-software, placing the aggregate frame into a boundary area wall, and realizing the conversion of aggregate particles into rigid clusters; performing DEM simulation to enable aggregates to collide freely until balance, and recording position information distributed after cluster collision in a geometric file; and then judging the contact property of aggregate entities in the geometric file by calling an aggregate contact judging algorithm developed by Python language, and cutting aggregates with contact and overlapping quantities to finally obtain the numerical simulation model of the high-volume-fraction mixed rock. The invention can generate the mixed rock numerical simulation model with extremely high volume fraction, avoid overlapping among aggregates, and better simulate the contact surface among aggregate particles.
Description
Technical Field
The invention belongs to the technical field of numerical simulation parameter research of heterogeneous rock-soil material mixed rock, and particularly relates to a method for generating a two-dimensional ultrahigh volume fraction mixed rock numerical simulation model by adopting an overlapping contact cutting algorithm.
Background
Due to the limitation of the experimental method and the rapid rise and development of the numerical simulation method, the mechanical parameters and mechanical properties of the mixed rock material are researched by the numerical simulation method, and the problems of sample integrity, sample disturbance, sample size, errors caused by experimental operation and the like in the in-situ experiment and the indoor experiment process can be well overcome.
The numerical simulation research has an important problem, namely the establishment of an experimental model, namely, the generation of a numerical model sample of aggregate grading and high aggregate volume fraction which meet the numerical simulation requirement. At present, no researchers basically generate a mixed rock model with aggregate volume fraction more than 90%; however, in laboratory tests, the aggregate volume fraction of the mixed rock sample has reached 90%, as for example, afifipore et al, mechanical behavior of bimrocks having high rock block proportion, increased the aggregate volume fraction of the mixed rock to 90%. Therefore, the ultra-high volume mixed rock numerical simulation model needs to be studied to solve the problems of errors and the like in-situ experiments and indoor experimental processes.
In the aspect of model establishment, the existing microscopic numerical simulation model generation methods mainly comprise two types, namely an image processing method; and secondly, a random block throwing method. The image processing method is to scan and image identify the section of the mixed rock sample so as to distinguish aggregate and matrix and build a model; however, the method has no method for researching the randomness of the internal material distribution of the mixed rock material and has certain limitation. The random block throwing method is used for generating random blocks through an algorithm, and throwing the blocks in a designated model boundary area by using a throwing algorithm, but contact is considered during throwing, so that the aggregate volume fraction of the generated mixed rock model is difficult to reach the requirement, and the mixed rock model with very high volume fraction is more difficult to generate.
Disclosure of Invention
The invention aims to provide a method for generating a two-dimensional ultra-high volume fraction mixed rock numerical simulation model by adopting an overlapping contact cutting algorithm, which solves the technical problem that the ultra-high volume fraction mixed rock model and the simulation aggregate are not really generated in the prior art.
In order to solve the technical problems, the invention adopts the following technical scheme:
a method for generating a two-dimensional ultrahigh volume fraction mixed rock numerical simulation model by adopting an overlapping contact cutting algorithm comprises the following steps:
step 1: and generating all polygonal aggregate frame geometric models according to the information such as the grain size distribution curve, the aggregate volume fraction and the like.
Step 2: generating rigid cluster clips with the same size and shape according to the polygonal aggregate frame by using discrete meta-software, and setting a model boundary as a wall boundary; the aggregate particles can be ensured to be in the boundary of the model, and meanwhile, the distribution of the aggregate on the boundary can be simulated;
step 3: after generating an aggregate rigid cluster and setting a boundary, simulating collision of the rigid cluster by using discrete elements to redistribute aggregate positions; acquiring coordinate information of the outline of the rigid aggregate clusters after the aggregate particles are redistributed after the aggregate particles collide and reach balance, obtaining a mixed rock geometric model with randomly distributed aggregate particles, and storing the mixed rock geometric model as a geometric file; the step can simulate random distribution of aggregate particles in mixed rock in nature, and allows the aggregate particles to be distributed at any position and at any angle and to be close to the actual situation;
step 4: calling a contact overlap judgment algorithm to process the mixed rock model geometric file; and (3) obtaining polygonal entities of all aggregate particles of the whole model, circularly traversing all the aggregate entities through the algorithm, finding aggregate with contact overlapping amount with surrounding polygonal aggregate particles, and judging the contact overlapping type.
Step 5: and cutting the aggregate with overlapped contact by adopting different contact overlap cutting algorithms according to the type of aggregate contact overlap, and updating corresponding aggregate information into a polygonal aggregate entity list after each cutting.
Step 6: and (5) repeating the step 5 for the updated aggregate entity list until all polygonal aggregates generating contact overlapping amount in the boundary are cut and updated. After cutting aggregate particles overlapped in a contact way, if the aggregate entity is not updated, once a certain aggregate is overlapped with a plurality of aggregates in a contact way, when a geometric file is exported again in a later period, the overlapped part of the cut is repeatedly drawn, and the cutting is failed; therefore, after each time step 5 is performed, the aggregate entity list needs to be updated until no contact overlap exists between any two aggregates.
Step 7: rewriting the cut polygonal aggregate into a geometric file by using a corresponding geometric figure derivation algorithm, and deriving; accumulating the areas of the aggregate particle entities in the derived geometric files to obtain the total area S of the aggregate particles in the final two-dimensional mixed rock model a And is connected with the area S of the boundary area of the model b And calculating the ratio to obtain the volume fraction of the cut aggregate.
Further preferably, in the step 1, the process of generating all polygonal aggregate frames is as follows:
step 1.1: in a polar coordinate system, taking an origin as a base point, obtaining a series of random radius and angle values through a random function, obtaining a series of random points according to the random radius and angle, and sequentially connecting the points to obtain polygonal aggregate;
step 1.2: the total area of all aggregates in the model boundary is obtained through accumulation; dividing according to the aggregate particle size intervals of the particle size distribution curve, and controlling the ratio of the aggregate in the corresponding particle size interval to the model according to the ratio of the area of the aggregate in the corresponding particle size interval to the total area of all aggregates;
step 1.3: and the total area of all aggregates is obtained through accumulation, and the volume fraction of the mixed rock model is controlled through the ratio of the total area of the aggregates to the area of the boundary area of the model.
Further preferably, the step 2 further includes the following steps: adopting a Minkowski algorithm, and expanding the outline of all aggregates outwards by expanding the outline of each side of the polygonal aggregate model outwards in a normal direction; and simulating the collision of the clusters by using discrete elements, and restoring the external contour of the aggregate to a state before expansion after the collision of the aggregate particles reaches balance. The boundary of the aggregate frame is extended outwards, which is equivalent to wrapping the aggregate with a shell, so that the overlap amount generated in the collision process of part of the aggregate is in the shell part, and when the external contour of the aggregate is restored to the state before extension, the contact overlap between part of the aggregate can disappear, namely the overlap between the aggregates is reduced, and the contact and overlap of the aggregate particles can be primarily controlled by controlling the extension distance.
Further preferably, in the step 2, the method for generating the rigid cluster specifically includes the following steps: generating a template of the rigid cluster by using polygonal frames of all aggregate particles, taking the template as a foundation for generating the rigid cluster with the same shape as the polygonal aggregate, and then automatically filling the rigid cluster template with the Pebble particles by using a foam Pack algorithm to obtain the rigid cluster. The bubble particles inside the rigid clusters (clips) are not deformed relatively, so that the rigid clusters (clips) cannot be damaged, the deformation and damage of the aggregate particles in collision are avoided, and the original aggregate shape is ensured.
Further preferably, in the step 3, the rigid cluster collision characteristic is as follows: in discrete element software, the collision between rigid clusters is simulated by a discrete unit method, the boundary of the model is set to be a rigid wall, rigidity is given to the rigid clusters, meanwhile, a contact model and rigidity are given to the rigid clusters of aggregate, and the wall and the aggregate are collided and sprung out when overlapped due to the rigidity; through mutual collision among the rigid aggregate clusters, bouncing off and collision between the rigid aggregate clusters and the wall boundary, the redistribution of the aggregate particles is realized, and the aggregate particles are allowed to exist on the boundary.
Further optimizing, in order to ensure that aggregate particles do not fly out of the boundary in collision, setting the rigidity of the wall to be far greater than the rigidity of the rigid aggregate clusters; contact between the aggregate and the wall can be difficult to contact between rigid clusters of aggregate; when the volume fraction is set to be large, a certain overlapping amount is generated between the rigid aggregate clusters due to the characteristic that the discrete element method allows the overlapping amount to exist, which is not in accordance with the actual situation.
To ensure the required volume fraction of the model, for aggregate particles on one side boundary wall, the part beyond the side boundary is placed on the other side boundary symmetrical to the periodic boundary; aggregate particles positioned on the boundary corner points of the model are divided into four parts, and are respectively placed into the four corner points corresponding to the boundary of the model through periodic boundaries.
In the step 4, a contact overlap judgment algorithm is adopted to judge the aggregate contact overlap type, and the method specifically comprises the following steps: the aggregate touch overlap type is judged by adopting a touch overlap judgment algorithm, and the concrete steps are as follows: reading the geometric file to obtain coordinate point information of each aggregate polygon; and then, a polygon contact overlap judgment algorithm is called to judge the contact overlap amount of the aggregate polygon.
The contact overlap of aggregate includes the following seven types:
1) The adjacent polygonal aggregates are in point-to-point contact;
2) The existence points between adjacent polygonal aggregates are in contact with the lines;
3) Line-to-line contact exists between adjacent polygonal aggregates;
4) The overlapping amount exists between adjacent polygonal aggregates, the overlapping part is a polygon, and the overlapping part is inside the boundary of the model and is not contacted with the boundary;
5) The overlapping amount exists between adjacent polygonal aggregates, the overlapping part is a plurality of polygons, and the overlapping part is inside the boundary of the model and is not contacted with the boundary;
6) The overlapping amount exists between the adjacent polygonal aggregates, the overlapping part is a polygon, and meanwhile, the overlapping part is contacted with the boundary of the model, and only one intersection point exists between the two polygonal aggregates.
7) The overlapping amount exists between adjacent polygonal aggregates, the overlapping part is a polygon, and meanwhile, the overlapping part is contacted with the boundary of the model, and the two polygonal aggregates have a plurality of intersection points.
Further preferably, in the step 5, different cutting modes are implemented according to different contact overlap types, and specifically the method is as follows:
1) The point-to-point contact between adjacent polygonal aggregates simulates the contact between sharp angles and sharp angles existing between aggregate particles in mixed rock under the actual condition, and the contact is allowed to exist without cutting.
2) The point-to-line contact between adjacent polygonal aggregates simulates the contact between sharp angles and surfaces existing between aggregate particles in mixed rock under the actual condition, and the contact is allowed to exist without cutting.
3) The line-to-line contact between adjacent polygonal aggregates simulates the surface-to-surface contact existing between aggregate particles in mixed rock in real conditions, allowing for the presence without cutting.
4) The overlapping amount exists between adjacent polygonal aggregates, the overlapping part is a polygon, and the overlapping part is positioned inside the boundary of the model and is not contacted with the boundary.
The overlapping aggregate for this case was cut as follows:
4.1 The method comprises the steps of) combining two aggregates with contact overlap by using a high-efficiency combination algorithm of a plurality of polygonal overlaps, combining polygons corresponding to the overlap portions, dissolving and combining intersecting lines at one point, combining repeated points to form a combined polygonal aggregate, and deleting the overlap portions.
4.2 Adopting a geometric figure intersection judging method to obtain an intersection of two polygonal aggregates with overlapping quantity; reading a geometric file, reading vertex information of a corresponding geometric figure, obtaining a set of vertex coordinates of polygons corresponding to the overlapped parts, and marking the set as a first set; generating a set of vertex coordinates of the two overlapped aggregates, and marking the set as a second set; then calculating to obtain an intersection of the first set and the second set, and marking the intersection as a third set; and finally, deleting the vertex coordinates in the third set from the first set, wherein the remaining two vertices are the intersection points of the two aggregates. Since the intersection point is located on the edge of the polygonal aggregate and cannot be found directly, the intersection point needs to be found by the method.
4.3 Through the two intersection points, cutting the combined polygonal aggregate into two aggregates without overlapping amount along the cutting lines.
5) The overlapping amount exists between adjacent polygonal aggregates, the overlapping part is a plurality of polygons, no contact is made with the boundary inside the model boundary, and the overlapping aggregate for the case is cut according to the following method:
5.1 The method comprises the steps of) combining two aggregates with contact overlap by using a high-efficiency combination algorithm of a plurality of polygonal overlaps, combining polygons corresponding to the overlap portions, dissolving and combining intersecting lines at one point, combining repeated points to form a combined polygonal aggregate, and deleting the overlap portions.
5.2 Adopting a geometric intersection judging method to obtain an intersection of two aggregates with overlapping quantity, wherein the intersection is a plurality of polygons, intersection point coordinates cannot be directly obtained, and the intersection point needs to be further traversed to obtain a vertex coordinate set of each polygon.
5.3 Calculating the distance between any two vertex coordinate points in the intersection, finding out two coordinate points with the largest distance to be the intersection of the aggregates, taking the two intersection points as cutting lines, and cutting the combined polygonal aggregate into two aggregates without overlapping amount along the cutting lines.
6) The overlapping amount exists between adjacent polygonal aggregates, the overlapping part is a polygon, and the overlapping part is contacted with the boundary of the model, so that the overlapping part is divided into two parts by the boundary of the side, one part is positioned near the boundary of the side, and the other part is positioned near the boundary of the other side symmetrical with the boundary of the side through a periodic boundary; the two shape aggregates in each part have only one intersection point, and the overlapping aggregates for this case are cut as follows:
6.1 The method comprises the steps of) combining two aggregates with contact overlap by using a high-efficiency combination algorithm of a plurality of polygonal overlaps, combining polygons corresponding to the overlap portions, dissolving and combining intersecting lines at one point, combining repeated points to form a combined polygonal aggregate, and deleting the overlap portions.
6.2 Obtaining an intersection of two aggregates with overlapping amount by adopting a geometric intersection judging method, wherein the overlapping part is contacted with the boundary, so that only one intersection point exists in the overlapping part, and the intersection point is found by adopting a method similar to the step 4.2); then traversing and judging the vertex coordinates of the intersection, and finding any vertex on the boundary as another intersection.
6.3 Cutting the combined polygonal aggregate into two aggregates without overlapping amount along the cutting line by taking the two intersection points as the cutting line; the other part, which is located near the symmetry border, is overlapped by cutting in the same way as described above.
7) The overlapping amount exists between adjacent polygonal aggregates, the overlapping part is a plurality of polygons, and the overlapping part is contacted with the boundary of the model, so that the overlapping part is divided into two parts by the boundary of the side, one part is positioned near the boundary of the side, and the other part is positioned near the boundary of the other side symmetrical to the boundary of the side through the periodic boundary; the two shape aggregates in each part have only a plurality of intersection points, and the overlapping aggregates for this case are cut as follows:
7.1 The method comprises the steps of) combining two aggregates with contact overlap by using a high-efficiency combination algorithm of a plurality of polygonal overlaps, combining polygons corresponding to the overlap portions, dissolving and combining intersecting lines at one point, combining repeated points to form a combined polygonal aggregate, and deleting the overlap portions.
7.2 By adopting a geometric intersection judging method, an intersection of two aggregates with overlapping quantity is obtained, and as the overlapping part is in contact with the boundary, a plurality of intersection points exist in the overlapping part, so that intersection point coordinates cannot be directly obtained, and the intersection points need to be further traversed to obtain vertex coordinate sets of each polygon.
7.3 Calculating the distance between any two vertex coordinate points in the intersection, finding out two coordinate points with the largest distance to be the intersection of the aggregates, taking the two intersection points as cutting lines, and cutting the combined polygonal aggregate into two aggregates without overlapping amount along the cutting lines; the other part, which is located near the symmetry border, is overlapped by cutting in the same way as described above.
In the step 7, the method for calculating the volume fraction of the cut aggregate of the mixed rock model specifically comprises the following steps:
step 7.1: reading a geometric model file of the cut polygonal aggregate;
step 7.2: calculating the area of each cut aggregate particle polygon, and accumulating the total area S of all cut aggregates a ；
Step 7.3: total area S of all aggregates after cutting a Area S of boundary area with model b And calculating the ratio to obtain the volume fraction of the cut aggregate. Since the model is a two-dimensional model, and is converted into a three-dimensional model and then has a sheet structure of equal thickness, the volume content can be expressed by an area ratio.
Compared with the prior art, the invention has the following beneficial effects:
the method well solves the problems that the existing ultra-high volume fraction mixed rock model is difficult to generate and aggregate has contact overlapping. And the requirements of surface-to-surface contact among aggregates and generation of an ultrahigh volume fraction mixed rock model are met through an aggregate contact overlapping cutting algorithm. According to the method, the problems that the ultra-high volume fraction mixed rock numerical model is difficult to generate and the aggregate contacts are overlapped are solved, the ultra-high volume fraction mixed rock numerical model is converted into the aggregate surface-to-surface contact through a cutting algorithm, the generated model is more practical, and the volume fraction and the authenticity of the numerical simulation model can be improved.
Drawings
FIG. 1 is a flow chart of a method for generating a two-dimensional ultra-high volume mixed rock numerical simulation model by adopting an overlapping contact cutting algorithm;
FIG. 2 is a simulated view of the aggregate frame of example 1;
FIG. 3 is a simulated view of an aggregate-encased Minkowski shell of example 1;
FIG. 4 is a simulation of the aggregate converted into rigid clusters and subjected to discrete element collisions in example 1;
FIG. 5 is a simulation of example 1 after impact, after aggregate dispersion equilibration;
FIG. 6 is an enlarged view of a portion of the portion A of FIG. 5, showing point-to-point contact between aggregates in a mixed rock model;
FIG. 7 is an enlarged view of a portion B of FIG. 5 showing point-to-line contact between aggregates in a mixed rock model;
FIG. 8 is an enlarged view of a portion C of FIG. 5, a contact overlap portion between aggregates in a mixed rock model being a single polygon and being inside a boundary;
FIG. 9 is a schematic view of a cutting step in which the contact overlapping portion between aggregates in a mixed rock model is a polygon and inside a boundary;
FIG. 10 is an enlarged view of a portion D of FIG. 5, showing the contact overlap between aggregates in the mixed rock model as a plurality of polygons and within the boundaries;
fig. 11 is a schematic view showing a cutting procedure for the contact overlapping portion between aggregates in the mixed rock model into a plurality of polygons and inside the boundary in example 1;
FIG. 12 is an enlarged view of a portion of the boundary of the contact overlap between aggregates in the mixed rock model at portion E in FIG. 5;
fig. 13 is a schematic view showing a cutting step on a boundary for a contact overlapping portion between aggregates in a mixed rock model in example 1;
fig. 14 is a final model diagram of the mixed rock model in example 1 after the contact overlap judgment and the cutting treatment;
FIG. 15 is a simulation of the aggregate dispersion balance of the mixed rock model of example 2 with an aggregate volume fraction of 95%;
fig. 16 is a final model diagram of the mixed rock model in example 2 after the contact overlap judgment and the cutting treatment;
FIG. 17 is a simulation of the aggregate dispersion balance in the mixed rock model of example 3 with 100% aggregate volume fraction;
fig. 18 is a final model diagram of the mixed rock model in example 3 after the contact overlap determination and the cutting process.
Detailed Description
The technical scheme of the invention will be clearly and completely described below with reference to the accompanying drawings; it will be apparent that the embodiments described below are some, but not all, embodiments of the invention. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1:
as shown in fig. 1, a method for generating a two-dimensional ultra-high volume fraction mixed rock numerical simulation model by adopting an overlapping contact cutting algorithm comprises the following steps:
step 1: and generating a geometrical model of the polygonal aggregate according to the grading curve and the aggregate volume fraction information by using Matlab software.
In this embodiment, the boundary size of the two-dimensional mixed rock model is set to 10cm×20cm, and the volume fraction of aggregate is 90%. The particle size distribution of the particle size grading is 4 intervals: [6.0,9.0], [9.0, 10.5], [10.5, 11.2], [11.2, 12], in mm. The aggregate in the corresponding particle size interval accounts for 19.6%, 47.9%, 24.5% and 8.0% of the total aggregate by volume, and the polygon is the geometric model of the aggregate as shown in figure 2. The method has no special requirement on the grain composition of the aggregate, and can be set at will.
Step 2: the Minkowski algorithm is adopted, and the normal direction of each side of the polygonal aggregate model is extended outwards, so that the extension and extension of the outline of all aggregates outwards are equivalent to wrapping the aggregates with a shell, as shown in figure 3. Generating a template of rigid clusters with the same size and shape by utilizing discrete meta-software through a polygonal framework of each aggregate particle, taking the template as a basis for generating the rigid clusters with the same shape as the polygonal aggregate, automatically filling the rigid cluster template with the Pebble particles through a Bubble Pack algorithm to obtain the rigid clusters (cluster), setting a model boundary as a periodic rigid wall boundary as shown in fig. 4, and simulating the distribution of the aggregate on the boundary.
Step 3: the impact of rigid clusters was simulated using discrete elements to redistribute aggregate positions as shown in fig. 5. And restoring the outer contour of the aggregate to the state before expansion. The rigidity of the model boundary wall is far greater than that of the aggregate rigid cluster; ensuring that aggregate particles do not fly out of the boundary in the collision process; for aggregate particles on one side boundary wall, the part beyond the side boundary is placed on the other side boundary symmetrical with the periodic boundary; aggregate particles positioned on the boundary corner points of the model are divided into four parts, and are respectively placed into the four corner points corresponding to the boundary of the model through periodic boundaries. And then acquiring coordinate information of the aggregate rigid cluster outline after redistribution to obtain a mixed rock geometric model with aggregate particles distributed randomly, and storing the mixed rock geometric model as dxf files.
Step 4: processing dxf files of the mixed rock geometric model by using a Python contact overlap judging algorithm; and (3) obtaining polygonal entities of all aggregate particles of the whole model, circularly traversing all the aggregate entities through the algorithm, finding aggregate with contact overlapping amount with surrounding polygonal aggregate particles, and judging the contact overlapping type.
Step 5: and cutting the aggregate with overlapped contact by adopting different contact overlap cutting algorithms according to the type of aggregate contact overlap, and updating corresponding aggregate information into a polygonal aggregate entity list after each cutting.
Different cutting modes are implemented according to different contact overlapping types, and the method is as follows:
1) Point-to-point contact between adjacent polygonal aggregates simulates the sharp angle-to-sharp angle contact existing between aggregate particles in mixed rock in real conditions, allowing for the presence without cutting, as shown in fig. 6.
2) The point-to-line contact between adjacent polygonal aggregates simulates the sharp angle-to-face contact that exists between aggregate particles in a mixed rock in a real-world situation, allowing for the presence without cutting, as shown in fig. 7.
3) The line-to-line contact between adjacent polygonal aggregates simulates the surface-to-surface contact existing between aggregate particles in mixed rock in real conditions, allowing for the presence without cutting.
4) The overlapping amount exists between adjacent polygonal aggregates, and the overlapping part is a polygon, the overlapping part is positioned inside the boundary of the model and is not in contact with the boundary, as shown in fig. 8, and the overlapping aggregate for the case is cut according to the following method:
combining the overlapped aggregate by using a high-efficiency combination method of a shape library in Python to form a combined polygonal aggregate, wherein the middle contact overlapped part is deleted; meanwhile, the intersection of two polygonal aggregates with overlapping amount is obtained by an intersection method in a shape library; acquiring a set of vertex coordinates of polygons corresponding to the overlapped part by a posts method of an entity in a dxfgrobber library, and marking the set as a first set; generating a set of vertex coordinates of the two overlapped aggregates, and marking the set as a second set; then calculating to obtain an intersection of the first set and the second set, and marking the intersection as a third set; finally, deleting the vertex coordinates in the third set from the first set, wherein the remaining two vertices are the intersection points of the two aggregates; then, the two intersection points are used as cutting lines, and the joint polygonal aggregate is cut into two aggregates without overlapping amount by using the split method in the shape warehouse, as shown in fig. 9.
5) There is an overlap amount between adjacent polygonal aggregates, and the overlap portion is a plurality of polygons, inside the model boundary, without contact with the boundary, as shown in fig. 10, the overlapping aggregates for this case are cut as follows:
combining the overlapped aggregate by using a high-efficiency combination method of a shape library in Python to form a combined polygonal aggregate, wherein the middle contact overlapped part is deleted; meanwhile, the intersection of the aggregate and another aggregate is returned by an intersection method in the shape library, but the intersection at this time is a plurality of polygons, so that the intersection vertex coordinates cannot be directly obtained, and the intersection needs to be further traversed to obtain the vertex coordinates of each single polygon; then, the scipy library and the numpy library are called to calculate the distance between each coordinate point in the intersection, the coordinate point with the largest distance is found to be the intersection of the aggregates, the two intersection points are used as cutting lines, and the joint polygonal aggregate is cut into two aggregates without overlapping amount by using the split method in the shape library, as shown in fig. 11.
6) The overlapping amount exists between adjacent polygonal aggregates, the overlapping part is a polygon, and the overlapping part is contacted with the boundary of the model, so that the overlapping part is divided into two parts by the boundary of the side, one part is positioned near the boundary of the side, and the other part is positioned near the boundary of the other side symmetrical with the boundary of the side through a periodic boundary; only one intersection of the two shaped aggregates in each section, as shown in fig. 12, the overlapping aggregates for this case were cut as follows:
combining aggregates with contact overlap by using a high-efficiency combination method of shape libraries in Python to form a combined polygonal aggregate, and deleting the overlapped part; obtaining an intersection of two aggregates with overlapping quantity by an intersection method in a shape library, wherein the overlapping part is in contact with a boundary, so that the overlapping part has only one intersection point, and the intersection point is found by a point method of an entity in a dxfgrobber library by a method similar to the step 4.2); traversing and judging the vertex coordinates of the intersection, and finding any vertex on the boundary as another intersection; the joint polygonal aggregate was cut into two aggregates without overlapping amounts by split in shape library by using these two intersections as cutting lines, as shown in fig. 13. The other part, which is located near the symmetry border, is overlapped by cutting in the same way as described above.
7) The overlapping amount exists between adjacent polygonal aggregates, the overlapping part is a plurality of polygons, and the overlapping part is contacted with the boundary of the model, so that the overlapping part is divided into two parts by the boundary of the side, one part is positioned near the boundary of the side, and the other part is positioned near the boundary of the other side symmetrical to the boundary of the side through the periodic boundary; the two shape aggregates in each part have only a plurality of intersection points, and the overlapping aggregates for this case are cut as follows:
combining aggregates with contact overlap by using a high-efficiency combination method of shape libraries in Python to form a combined polygonal aggregate, and deleting the overlapped part; acquiring an intersection of two aggregates with overlapping quantity by an intersection method in a shape library, wherein the overlapping part is contacted with a boundary, so that a plurality of intersection points exist in the overlapping part, the intersection point coordinates of the intersection cannot be directly acquired, the intersection is required to be further traversed, and the vertex coordinate set of each polygon is acquired by a ponits method of an entity in a dxfgrobber library; invoking a scipy library and a numpy library, calculating the distance between any two vertex coordinate points in the intersection, finding out two coordinate points with the largest distance as intersection points of aggregates, taking the two intersection points as cutting lines, and cutting the combined polygonal aggregates into two aggregates without overlapping amount by using a split method in the shape library; the other part, which is located near the symmetry border, is overlapped by cutting in the same way as described above.
Step 6: and (5) repeating the step 5 for the updated aggregate entity list until all polygonal aggregates generating contact overlapping amount in the boundary are cut and updated. After the processing of the contact overlap cutting algorithm, two polygonal aggregates with contact overlap amount are cut into two polygonal aggregates with only one line overlapping contact.
Step 7: rewriting the cut polygonal aggregate into dxf file and deriving the dxf file by using the corresponding dxfgrobber library in Python, wherein the final geometric model is shown in fig. 14 (the difference between fig. 14 and fig. 5 is that contact overlap exists between some adjacent aggregates in fig. 5, and the overlapped part between adjacent aggregates in fig. 14 is already cut); then, calling a shape library corresponding to Python, and accumulating the areas of aggregate particle entities in the derived dxf file by using a polygonal area method to obtain the total area S of the aggregate particles in the final two-dimensional mixed rock model a And is connected with the area S of the boundary area of the model b And calculating the ratio to obtain the volume fraction of the cut aggregate. Since the deformation of the corresponding pair of cut aggregates into vertex coordinates is known, the area of each aggregate is also known. The aggregate volume fraction after cutting of the model of this example is 89.17%, the error between theory and practice is 0.83%, which is less than the set error value of 1%, thus satisfying the volume fraction set by the model.
Embodiment two:
by adopting the same method as in the first embodiment, a mixed rock model with the aggregate volume fraction set to 95% is generated, and a simulation diagram after aggregate dispersion balance is shown in fig. 15; after the aggregate is processed by a cutting algorithm, a mixed rock geometric model with the aggregate volume fraction of 92.26% is obtained, as shown in fig. 16.
Embodiment III:
adopting the same method as in the first embodiment, a mixed rock model with the aggregate volume fraction set to 100% is generated, and a simulation diagram after aggregate dispersion balance is shown in fig. 17; after the division is processed by a cutting algorithm, a mixed rock geometric model with the aggregate volume fraction of 95.25% is obtained, as shown in fig. 18. As long as the set volume fraction is increased, the method can be used for generating a geometric model with the aggregate volume fraction close to 100%.
The invention is not only suitable for generating the ultra-high volume fraction mixed rock numerical simulation model, but also suitable for heterogeneous rock-soil materials such as concrete, soil-rock mixtures and the like.
The foregoing description is only illustrative of the present invention and is not intended to limit the scope of the invention, and all equivalent structures or equivalent processes or direct or indirect application in other related technical fields are included in the scope of the present invention.
Claims (9)
1. The method for generating the two-dimensional ultrahigh volume fraction mixed rock numerical simulation model by adopting the overlapping contact cutting algorithm is characterized by comprising the following steps of:
step 1: generating two-dimensional frame geometric models of all polygonal aggregates according to the particle grading curve and the aggregate volume fraction information;
step 2: generating rigid clusters with the same size and shape according to a polygonal aggregate frame by using discrete meta-software, setting a model boundary as a wall boundary, ensuring that aggregate particles can be in the model boundary, and simulating the distribution of aggregates on the boundary;
step 3: simulating collision of the rigid clusters by using discrete elements to redistribute aggregate positions; acquiring coordinate information of the outline of the rigid aggregate clusters after the aggregate particles are redistributed after the aggregate particles collide and reach balance, obtaining a mixed rock geometric model with randomly distributed aggregate particles, and storing the mixed rock geometric model as a geometric file;
step 4: adopting a contact overlap judging algorithm to process the geometric file of the mixed rock model to obtain polygonal entities of all aggregate particles of the whole model, circularly traversing all the aggregate entities, searching aggregate with contact overlap amount with surrounding polygonal aggregate particles, and judging the contact overlap type;
step 5: cutting the contact overlapped aggregate by adopting different contact overlap cutting algorithms according to the aggregate contact overlap type, and updating corresponding aggregate information into a polygonal aggregate entity list after each cutting;
step 6: repeating the step 5 for the updated aggregate entity list until all polygonal aggregates generating contact overlapping amount in the boundary are cut and updated;
step 7: rewriting the polygonal aggregate subjected to cutting into a geometric file and exporting the geometric file; and for derived geometryAccumulating the areas of the aggregate particle entities in the file to obtain the total area S of the aggregate particles in the final two-dimensional mixed rock model a And is connected with the area S of the boundary area of the model b And calculating the ratio to obtain the volume fraction of the cut aggregate.
2. The method for generating a two-dimensional ultrahigh volume fraction mixed rock numerical simulation model by adopting an overlapping contact cutting algorithm according to claim 1, wherein in the step 1, the process of generating all polygonal aggregate frames is as follows:
step 1.1: in a polar coordinate system, taking an origin as a base point, obtaining a series of random radius and angle values through a random function, obtaining a series of random points according to the random radius and angle, and sequentially connecting the points to obtain polygonal aggregate;
step 1.2: the total area of all aggregates in the model boundary is obtained through accumulation; dividing according to the aggregate particle size intervals of the particle size distribution curve, and controlling the ratio of the aggregate in the corresponding particle size interval to the model according to the ratio of the area of the aggregate in the corresponding particle size interval to the total area of all aggregates;
step 1.3: and the total area of all aggregates is obtained through accumulation, and the volume fraction of the mixed rock model is controlled through the ratio of the total area of the aggregates to the area of the boundary area of the model.
3. The method for generating a two-dimensional ultrahigh volume fraction mixed rock numerical simulation model by adopting an overlapping contact cutting algorithm according to claim 2, wherein the step 2 further comprises the following steps: adopting a Minkowski algorithm, and expanding the outline of all aggregates outwards by expanding the outline of each side of the polygonal aggregate model outwards in a normal direction; and simulating the collision of the clusters by using discrete elements, and restoring the external contour of the aggregate to a state before expansion after the collision of the aggregate particles reaches balance.
4. The method for generating a two-dimensional ultrahigh volume fraction mixed rock numerical simulation model by adopting an overlapping contact cutting algorithm according to claim 3, wherein in the step 2, the method for generating the rigid clusters is specifically as follows: generating a template of the rigid cluster by using polygonal frames of all aggregate particles, taking the template as a foundation for generating the rigid cluster with the same shape as the polygonal aggregate, and then adopting a Bubble Pack algorithm to automatically fill the rigid cluster template with the Pebble particles to obtain the rigid cluster.
5. The method for generating a two-dimensional ultrahigh volume fraction mixed rock numerical simulation model by using an overlap contact cutting algorithm according to claim 4, wherein in the step 3, the rigid cluster collision characteristics are as follows:
the method comprises the steps of simulating collision among rigid clusters in discrete element software through a discrete unit method, wherein the boundary of a model is rectangular, setting the boundary of the model into a rigid wall, endowing rigidity to the rigid cluster, and endowing contact model and rigidity to the rigid cluster of aggregate, wherein the collision and flicking are caused when the wall and the aggregate are overlapped due to the rigidity; through mutual collision among the rigid aggregate clusters, bouncing off and collision between the rigid aggregate clusters and the wall boundary, the redistribution of aggregate particles is realized, and the aggregate particles are allowed to exist on the boundary of the model.
6. The method for generating a two-dimensional ultrahigh volume fraction mixed rock numerical simulation model by adopting an overlapping contact cutting algorithm according to claim 5, wherein the method comprises the steps of,
the rigidity of the model boundary wall is far greater than that of the aggregate rigid cluster; for aggregate particles on one side boundary wall, the part beyond the side boundary is placed on the other side boundary symmetrical with the periodic boundary; aggregate particles positioned on the boundary corner points of the model are divided into four parts, and are respectively placed into the four corner points corresponding to the boundary of the model through periodic boundaries.
7. The method for generating the two-dimensional ultrahigh volume fraction mixed rock numerical simulation model by adopting the overlapping contact cutting algorithm according to claim 6, wherein in the step 4, the contact overlapping type is judged by adopting a contact overlapping judgment algorithm, and the method is specifically as follows: reading the geometric file to obtain coordinate point information of each aggregate polygon; then, a polygon contact overlap judgment algorithm is called to judge the contact overlap amount of the aggregate polygon;
the contact overlap of aggregate includes the following seven types:
1) The adjacent polygonal aggregates are in point-to-point contact;
2) The existence points between adjacent polygonal aggregates are in contact with the lines;
3) Line-to-line contact exists between adjacent polygonal aggregates;
4) The overlapping amount exists between adjacent polygonal aggregates, the overlapping part is a polygon, and the overlapping part is inside the boundary of the model and is not contacted with the boundary;
5) The overlapping amount exists between adjacent polygonal aggregates, the overlapping part is a plurality of polygons, and the overlapping part is inside the boundary of the model and is not contacted with the boundary;
6) The overlapping amount exists between adjacent polygonal aggregates, the overlapping part is a polygon, and meanwhile, the overlapping part is contacted with the boundary of the model, and only one intersection point exists between the two polygonal aggregates;
7) The overlapping amount exists between the adjacent polygonal aggregates, the overlapping part is a plurality of polygons, and meanwhile, the overlapping part is contacted with the boundary of the model, and the two polygonal aggregates have a plurality of intersection points.
8. The method for generating the two-dimensional ultrahigh volume fraction mixed rock numerical simulation model by adopting the overlapping contact cutting algorithm according to claim 7, wherein in the step 5, different cutting modes are implemented according to different contact overlapping types, specifically comprising the following steps:
1) Point-to-point contact between adjacent polygonal aggregates simulates the contact between sharp angles and sharp angles existing between aggregate particles in mixed rock under the actual condition, and the contact is allowed to exist without cutting;
2) The point-to-line contact between adjacent polygonal aggregates simulates the contact between sharp angles and surfaces existing between aggregate particles in mixed rock under the actual condition, and the contact is allowed to exist without cutting;
3) The line-to-line contact between adjacent polygonal aggregates simulates the surface-to-surface contact existing between aggregate particles in mixed rock under real conditions, and the surface-to-surface contact is allowed to exist without cutting;
4) The overlapping amount exists between adjacent polygonal aggregates, the overlapping part is a polygon, the overlapping part is positioned inside the boundary of the model and is not contacted with the boundary, and the overlapping aggregates for the situation are cut according to the following method:
4.1 Combining two aggregates with contact overlap by using a high-efficiency combination algorithm of a plurality of polygonal overlaps, combining polygons corresponding to the overlap, dissolving and combining intersecting lines at one point, combining repeated points to form a combined polygonal aggregate, and deleting the overlap;
4.2 Adopting a geometric figure intersection judging method to obtain an intersection of two polygonal aggregates with overlapping quantity; reading a geometric file, obtaining a set of vertex coordinates of polygons corresponding to the overlapped parts, and marking the set as a first set; generating a set of vertex coordinates of the two overlapped aggregates, and marking the set as a second set; then calculating to obtain an intersection of the first set and the second set, and marking the intersection as a third set; finally, deleting the vertex coordinates in the third set from the first set, wherein the remaining two vertices are the intersection points of the two aggregates;
4.3 Cutting the combined polygonal aggregate into two aggregates without overlapping amount along the cutting line by taking the two intersection points as the cutting line;
5) The overlapping amount exists between adjacent polygonal aggregates, the overlapping part is a plurality of polygons, no contact is made with the boundary inside the model boundary, and the overlapping aggregate for the case is cut according to the following method:
5.1 Combining two aggregates with contact overlap by using a high-efficiency combination algorithm of a plurality of polygonal overlaps, combining polygons corresponding to the overlap, dissolving and combining intersecting lines at one point, combining repeated points to form a combined polygonal aggregate, and deleting the overlap;
5.2 Obtaining an intersection of two aggregates with overlapping amount by adopting a geometric intersection judging method, wherein the intersection is a plurality of polygons, intersection point coordinates cannot be directly obtained, and the intersection point needs to be further traversed to obtain a vertex coordinate set of each polygon;
5.3 Calculating the distance between any two vertex coordinate points in the intersection, finding out two coordinate points with the largest distance to be the intersection of the aggregates, taking the two intersection points as cutting lines, and cutting the combined polygonal aggregate into two aggregates without overlapping amount along the cutting lines;
6) The overlapping amount exists between adjacent polygonal aggregates, the overlapping part is a polygon, and the overlapping part is contacted with the boundary of the model, so that the overlapping part is divided into two parts by the boundary of the side, one part is positioned near the boundary of the side, and the other part is positioned near the boundary of the other side symmetrical with the boundary of the side through a periodic boundary; the two shape aggregates in each part have only one intersection point, and the overlapping aggregates for this case are cut as follows:
6.1 Combining two aggregates with contact overlap by using a high-efficiency combination algorithm of a plurality of polygonal overlaps, combining polygons corresponding to the overlap, dissolving and combining intersecting lines at one point, combining repeated points to form a combined polygonal aggregate, and deleting the overlap;
6.2 Obtaining an intersection of two aggregates with overlapping amount by adopting a geometric intersection judging method, wherein the overlapping part is contacted with the boundary, so that only one intersection point exists in the overlapping part, and the intersection point is found by adopting a method similar to the step 4.2); traversing and judging the vertex coordinates of the intersection, and finding any vertex on the boundary as another intersection;
6.3 Cutting the combined polygonal aggregate into two aggregates without overlapping amount along the cutting line by taking the two intersection points as the cutting line; the other part of the overlapping amount near the symmetrical boundary is cut by adopting the same method as the above;
7) The overlapping amount exists between adjacent polygonal aggregates, the overlapping part is a plurality of polygons, and the overlapping part is contacted with the boundary of the model, so that the overlapping part is divided into two parts by the boundary of the side, one part is positioned near the boundary of the side, and the other part is positioned near the boundary of the other side symmetrical to the boundary of the side through the periodic boundary; the two shape aggregates in each part have a plurality of intersection points, and the overlapping aggregates for this case are cut as follows:
7.1 Combining two aggregates with contact overlap by using a high-efficiency combination algorithm of a plurality of polygonal overlaps, combining polygons corresponding to the overlap, dissolving and combining intersecting lines at one point, combining repeated points to form a combined polygonal aggregate, and deleting the overlap;
7.2 Adopting a geometric intersection judging method to obtain an intersection of two aggregates with overlapping quantity, wherein the overlapping part is contacted with the boundary, so that a plurality of intersection points exist in the overlapping part, the intersection point coordinates of the intersection points cannot be directly obtained, and the intersection points need to be further traversed to obtain vertex coordinate sets of each polygon;
7.3 Calculating the distance between any two vertex coordinate points in the intersection, finding out two coordinate points with the largest distance to be the intersection of the aggregates, taking the two intersection points as cutting lines, and cutting the combined polygonal aggregate into two aggregates without overlapping amount along the cutting lines; the other part, which is located near the symmetry border, is overlapped by cutting in the same way as described above.
9. The method for generating the two-dimensional ultrahigh volume fraction mixed rock numerical simulation model by adopting the overlapping contact cutting algorithm according to claim 8, wherein in the step 7, the method for calculating the volume fraction of the cut mixed rock model aggregate is specifically as follows:
step 7.1: reading a geometric model file of the cut polygonal aggregate;
step 7.2: calculating the area of each cut aggregate particle polygon, and accumulating the total area S of all cut aggregates a ；
Step 7.3: total area S of all aggregates after cutting a Area S of boundary area with model b And calculating the ratio to obtain the volume fraction of the cut aggregate.
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