Rock mass rough opening fracture grid generation method and device based on parting iteration method, medium and equipment

Abstract

The invention discloses a rock mass rough opening fracture grid generation method and device based on a parting iteration method, a medium and equipment, and belongs to the technical field of rock mass structure geometric simulation research. The method comprises the following steps: generating a two-dimensional straight closed fracture model according to fracture geometric parameters and statistical distribution rules; each straight line segment is converted into three zigzag lines, and all the three lines are rotated to 0 degree in the clockwise direction; using a parting iteration method to enable each rotated three-section line to generate a rough closed fracture; sequentially connecting the starting point, the ascending point, the ending point and the descending point to form an open fracture, and deleting all points except the starting point and the ending point on the closed fracture; recovering to the same inclination angle of the corresponding straight line segment; and obtaining a final grid containing the rough open fractures. The device, the medium and the equipment can be used for realizing the method. According to the method, the complex geometrical shape and width distribution of the opening fracture and the inclination angle of any angle can be reproduced, so that the research result is more fit with the actual condition of the rock mass.

Description

Technical Field

[0001] This invention relates to the field of rock mass structure geometry simulation research technology, and in particular to a method, apparatus, medium and equipment for generating rough open fracture meshes in rock masses based on the fractal iteration method. Background Technology

[0002] As a product of geological movement, rock masses contain numerous fissures, resulting in extremely complex mechanical properties. When their initial geological environment is disturbed, such as by earthquakes or foundation excavation, these internal fissures can expand and transform into open fissures, further weakening the rock mass's bearing capacity.

[0003] Current technologies for studying fractures within rock masses typically rely on a few simple, newly formed fractures, which differ significantly from the actual fractures within the rock mass. Furthermore, obtaining undisturbed rock samples is extremely difficult, as the drilling process disturbs surrounding fractures, altering the acquired data. While methods such as lidar and CT scans can acquire fracture information, these methods place high demands on cost and equipment. Summary of the Invention

[0004] In view of this, the present invention provides a method, apparatus, medium and equipment for generating rough open fracture meshes in rock masses based on the fractal iteration method. It can reproduce the complex geometry and width distribution of open fractures, as well as the dip angle of arbitrary angles. Therefore, the research results are more consistent with the actual situation of rock masses, and thus more suitable for practical use.

[0005] To achieve the first objective mentioned above, the technical solution of the rock mass rough opening fracture mesh generation method based on the fractal iteration method provided by the present invention is as follows:

[0006] The method for generating rough open fracture meshes in rock mass based on the fractal iteration method provided by this invention includes the following steps:

[0007] S1: Establish a two-dimensional rectangular coordinate system XOY, and generate a two-dimensional straight closed fracture model based on the set fracture geometric parameters and statistical distribution law. This straight closed fracture model includes multiple straight line segments representing fractures.

[0008] S2: By randomly selecting points near the quarter point and vertically translating them, each straight line segment is transformed into a zigzag three-segment line, and all three-segment lines are rotated clockwise to 0°, that is, the line connecting the start and end points of the three-segment lines is parallel to the X-axis;

[0009] S3: Set the vertical scaling factor and the number of iterations, and use the fractal iteration method to generate a rough closed crack for each rotated three-segment line;

[0010] S4: Move each point on each closed fracture, except for the start and end points, randomly a certain distance in the positive direction of the Y-axis, and record the moved point as the ascending point; then move each point on each closed fracture, except for the start and end points, in the negative direction of the Y-axis by the same distance as the positive direction of the Y-axis, and record the moved point as the descending point; connect the start, ascending, end, and descending points in sequence to form an open fracture, and delete all points on the closed fracture except for the start and end points;

[0011] S5: Using the tilt angle recovery formula, rotate each open crack counterclockwise around its starting point by the corresponding angle to restore it to the same tilt angle as the corresponding straight line segment in step S1; the tilt angle of the closed rough open crack is the angle between the line connecting its starting point and ending point and the X-axis.

[0012] S6: Preserve the geometric features of the open crack and use mesh generation software to obtain the final mesh containing the coarse open crack.

[0013] The method for generating rough open fracture meshes in rock mass based on the fractal iteration method provided by this invention can be further implemented using the following technical measures.

[0014] Preferably, in step S1, the geometric parameters of the cracks include the number of cracks, their location distribution, length distribution, width distribution, number of cracks, and inclination angle.

[0015] In the statistical distribution of fracture parameters, the fracture location distribution is set to a relatively random distribution;

[0016] The dip angle β of all cracks can be set to a range or a fixed value, between 0° and 90°;

[0017] Assume that the length values ​​of all cracks follow a log-normal distribution, and that the probability density of their lengths satisfies the following formula:

[0018]

[0019] Where L is the length of the crack, lnL is the natural logarithm of the length (i.e., lnL follows a normal distribution); σ1 is the standard deviation of the length lnL, and μ1 is the mean of lnL, calculated using an integral formula. The mean crack length was obtained as follows.

[0020] Assume that the width values ​​of all cracks follow a Gaussian distribution, and the probability density formula for its width distribution is as follows:

[0021]

[0022] Where W is the width of the crack, σ2 is the standard deviation of the width, and the mean of the width is μ2.

[0023] As a preferred approach, based on the statistical distribution pattern in S1, the steps for generating a straight closed crack are as follows:

[0024] S1.1: Define the size boundaries of the mesh model, including the length and width of the entire model;

[0025] S1.2: Randomly select a point inside the model as the midpoint of the straight closed crack. Extend the crack in the opposite direction from the midpoint to both sides according to the set dip angle and length distribution law to obtain the start point and end point of the crack. Connect the start point and end point to form a straight line segment representing the crack.

[0026] S1.3: Determine whether the start and end points exceed the model boundaries:

[0027] If it does not exceed the limit, proceed to step S1.4;

[0028] If it exceeds the boundary, the straight line segment is shifted inwards towards the model boundary to ensure that the crack is within the model boundary.

[0029] S1.4: Calculate the distance Δd between the straight line segment and the cracks that have already formed inside the model. i And determine Δd i Is it less than the set distance d? min If the distance is less than d, move the line segment until the distance between the line segment and all other existing fractures is greater than or equal to d. min ;

[0030] S1.5: Repeat S1.2-1.4 until the set number of cracks are generated.

[0031] Preferably, the set distance d in S1.4 min The set quantity is 10% of the average length of the crack.

[0032] Preferably, step S2 specifically includes the following steps:

[0033] S2.1: Take two points on the straight line segment representing the crack, such that the midpoint and these two points divide the straight line segment into four equal parts. These two points are denoted as the first quarter point and the second quarter point, respectively.

[0034] Setting (x) s ,y s ), (x m ,y m ), (x e ,y e (x) represents the coordinates of the start point, midpoint, and end point of the fracture, respectively. q1 ,y q1 ) and (x q2 ,y q2 Let be the coordinates of the first and second quarter points, respectively.

[0035] x q1 =(x s +x m ) / 2,y q1 =(y s +y m ) / 2 (2-1)

[0036] x q2 =(x m +x e ) / 2,y q2 =(y m +y e ) / 2 (2-2)

[0037] S2.2: Using the first quarter point and the second quarter point as the center, set two intervals on the crack, with the length of each interval being 20% ​​of the crack length, and select a point from each interval;

[0038] S2.3: Move one of the points randomly to one side of the line segment by a certain distance, and denote it as the first fixed point; move the other point to the other side of the line segment by a certain distance, and denote it as the second fixed point;

[0039] Connect the starting point, the first fixed point, the second fixed point, and the ending point in sequence to form a three-segment line;

[0040] S2.4: Rotate the resulting three line segments clockwise around the starting point until the inclination angle of the three line segments is 0°, that is, the line connecting the starting and ending points of the three line segments is parallel to the X-axis; the rotation formula is as follows:

[0041]

[0042] Among them, (x i ,y i Let (i) be the coordinates of the i-th point on the three segments before rotation. When i = 1, it is the starting point (x). s ,y s ), i = n, which is the endpoint (x e ,y e );

[0043] (x j ,y j Let (x1, y1) be the j-th point on the three segments after rotation, where 1 ≤ j ≤ n. When j = 1, it is the starting point (x1, y1); when j = n, it is the ending point (x1, y1). n ,y n );

[0044] β is the dip angle of the fracture.

[0045] Preferably, in step S2.4, the distances the two points move can be the same or different, and the moving distance is 5%-10% of the crack length.

[0046] Preferably, in step S3, the steps for setting the vertical scaling factor and the number of iterations, and generating a rough closed crack using the fractal iteration method are as follows:

[0047] S3.1: After rotation, the points {(x) on the three segments are rotated. j ,y j )} is used as the initial set of interpolation points, and a fractal iteration is performed, x1 <x2<…<x j <… <x n-1 <x n Points k and x generated based on the fractal iteration method j <x k <x j+1 Its coordinates (x k ,y k The following formula can be used to calculate:

[0048]

[0049] Among them, a j ,c j ,e j , and f j These are the variables in the fractal iteration, and their respective calculation formulas are as follows:

[0050] a j =(x j+1 -x j ) / (x n -x1) (3-2)

[0051] c j =[(y j+1 -y j )-d×(y n -y1)] / (x n -x1) (3-3)

[0052] e j =(x n ×x j -x1×x j+1 ) / (x n -x1) (3-4)

[0053]

[0054] S3.2: Take the points on the curve after step S3.1 iteration as the initial set of interpolation points, and repeat the above steps to perform secondary fractal iteration; the curve after fractal iteration forms a rough closed crack.

[0055] Preferably, in step S4, the mean distance moved by each point other than the starting point and the ending point is μ1 / 2, and the standard deviation is σ1 / 2; at this time, the width distribution of the opening crack follows the probability density formula of the width distribution in step S1, i.e., formula (1-2).

[0056] Preferably, in step S5, the process of restoring the inclination angle of the open fracture is achieved by rotating all points on the open fracture counterclockwise by β around the starting point, as shown in the following formula:

[0057]

[0058] Among them, (x mi ,y mi ) and (x fi ,y fi The points are the points on the open fracture with an initial dip angle of 0° and the points on the final open fracture after the dip angle β is restored.

[0059] Preferably, in step S6, after preserving the geometric features of the opening cracks, the mesh is divided as follows: all the edge curves of the opening cracks and the model boundary are set as the boundaries of the mesh model, and meshing is performed; that is, the area where the opening cracks intersect with the model boundary is formed into a mesh.

[0060] To achieve the second objective mentioned above, the technical solution of the rock mass rough opening fracture mesh generation device based on the fractal iteration method provided by the present invention is as follows:

[0061] The present invention provides a rock mass rough opening fracture mesh generation device based on the fractal iteration method, characterized in that it includes:

[0062] The two-dimensional straight closed fracture model generation module is used to establish a two-dimensional rectangular coordinate system XOY and generate a two-dimensional straight closed fracture model based on the set fracture geometric parameters and statistical distribution law. The straight closed fracture model includes multiple straight line segments representing the fracture.

[0063] The line segment conversion module is used to convert each straight line segment into a zigzag three-segment line by vertically translating a randomly selected point near the quarter point, and then rotating all three-segment lines clockwise to 0°, that is, the line connecting the start and end points of the three-segment lines is parallel to the X-axis.

[0064] The coarse closed-slit generation module is used to set the vertical scaling factor and the number of iterations. It uses the fractal iteration method to generate coarse closed-slits for each rotated tri-segment line.

[0065] The open fracture forming module is used to randomly move each point on each closed fracture, except for the start and end points, a certain distance in the positive direction of the Y-axis, and record the moved points as the upward points; then, each point, except for the start and end points, is moved in the negative direction of the Y-axis by the same distance as the positive direction of the Y-axis, and the point after this movement is recorded as the downward point; the start point, upward point, end point, and downward point are connected in sequence to form an open fracture, and all points on the closed fracture, except for the start and end points, are deleted;

[0066] An angle rotation module is used to rotate each open crack counterclockwise around its starting point by a corresponding angle using the tilt angle recovery formula, so that it is restored to the same tilt angle as the corresponding straight line segment in step S1; the tilt angle of the closed rough open crack is the angle between the line connecting its starting point and ending point and the X-axis;

[0067] The crack mesh generation module is used to preserve the geometric features of open cracks and to obtain the final mesh containing coarse open cracks using mesh generation software.

[0068] To achieve the third objective mentioned above, the technical solution of the computer-readable storage medium provided by the present invention is as follows:

[0069] The present invention provides a computer-readable storage medium storing a program for generating rough open fracture meshes in rock mass based on the fractal iteration method. When the program is executed by a processor, it implements the steps of the method for generating rough open fracture meshes in rock mass based on the fractal iteration method provided by the present invention.

[0070] To achieve the fourth objective mentioned above, the technical solution for the electronic device provided by this invention is as follows:

[0071] The electronic device provided by the present invention is characterized in that it includes a memory and a processor. The memory stores a program for generating rough open fracture meshes in rock mass based on the fractal iteration method. When the program for generating rough open fracture meshes in rock mass based on the fractal iteration method is executed by the processor, it implements the steps of the method for generating rough open fracture meshes in rock mass based on the fractal iteration method provided by the present invention.

[0072] The present invention provides a method, apparatus, medium, and equipment for generating rough open fracture meshes in rock masses based on a fractal iteration method. By improving the fractal iteration method, it can perform fractal iteration on straight lines and rough curves with arbitrary dip angles, and can form rough open fractures by processing rough closed fractures. Furthermore, this method can control the length, width, dip angle, and number of fractures through relevant parameters, enabling a more accurate description of open fractures and providing technical support for mesh modeling in subsequent numerical simulations. Attached Figure Description

[0073] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0074] Figure 1 The flowchart illustrates a method for generating coarse open crack meshes using an improved fractal iteration method.

[0075] Figure 2 (a) A schematic diagram of generating relatively randomly distributed straight closed cracks in step S1;

[0076] Figure 2 (b) is Figure 2 (a) Schematic diagram of the crack moving inward toward the boundary;

[0077] Figure 3 This is a schematic diagram of the three line segments with an inclination angle of 0° generated in step S2.

[0078] Figure 4 (a) is a schematic diagram of the effect of different vertical scaling factors (d) on the roughness of closed cracks in step S3;

[0079] Figure 4 (b) is a schematic diagram showing the effect of different number of iterations (T) in step S3 on the smoothness of closed cracks;

[0080] Figure 5 This is a schematic diagram of step S4, which involves generating corresponding open cracks based on rough closed cracks, as well as tilt angle recovery and mesh generation.

[0081] Figure 6 This is a diagram showing the distribution of rough-opening cracks in Example 1.

[0082] Figure 7 This is the final mesh model for Example 1;

[0083] Figure 8 The images show actual open-crack diagrams from relevant papers;

[0084] Figure 9 Distribution diagram of rough-opening cracks in Example 2;

[0085] Figure 10 This is the final mesh model for Example 2;

[0086] Figure 11 The images show actual open-crack diagrams from relevant papers;

[0087] Figure 12A schematic diagram of the signal flow relationship between the functional modules in the rock mass rough opening fracture grid generation device based on the fractal iteration method provided by the present invention;

[0088] Figure 13 A schematic diagram of the structure of a rock mass rough opening fracture mesh generation device based on the fractal iteration method, which provides the hardware operating environment for embodiments of the present invention. Detailed Implementation

[0089] To address the problems existing in the prior art, this invention provides a method, apparatus, medium, and equipment for generating rough open fracture meshes in rock masses based on the fractal iteration method. It can reproduce the complex geometry and width distribution of open fractures, as well as the dip angle of arbitrary angles. Therefore, the research results are more consistent with the actual situation of rock masses, making it more suitable for practical use.

[0090] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the following, in conjunction with the accompanying drawings and preferred embodiments, details the specific implementation, structure, features, and effects of the method, apparatus, medium, and equipment for generating rough open fracture meshes in rock mass based on the fractal iteration method proposed by the present invention. In the following description, different "an embodiment" or "an embodiment" do not necessarily refer to the same embodiment. Furthermore, features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0091] In this article, the term "and / or" is merely a description of the relationship between related objects, indicating that there can be three relationships, such as A and / or B. Specifically, it can mean that A and B can be included at the same time, A can exist alone, or B can exist alone, and any of the above three situations can be met.

[0092] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0093] The method for generating rough open fracture meshes in rock mass based on the fractal iteration method provided by this invention includes the following steps:

[0094] S1: Establish a two-dimensional rectangular coordinate system XOY, and generate a two-dimensional straight closed fracture model based on the set fracture geometric parameters and statistical distribution law. This straight closed fracture model includes multiple straight line segments representing fractures.

[0095] S2: By randomly selecting points near the quarter point and vertically translating them, each straight line segment is transformed into a zigzag three-segment line, and all three-segment lines are rotated clockwise to 0°, that is, the line connecting the start and end points of the three-segment lines is parallel to the X-axis;

[0096] S3: Set the vertical scaling factor and the number of iterations, and use the fractal iteration method to generate a rough closed crack for each rotated three-segment line;

[0097] S4: Move each point on each closed fracture, except for the start and end points, randomly a certain distance in the positive direction of the Y-axis, and record the moved point as the ascending point; then move each point on each closed fracture, except for the start and end points, in the negative direction of the Y-axis by the same distance as the positive direction of the Y-axis, and record the moved point as the descending point; connect the start, ascending, end, and descending points in sequence to form an open fracture, and delete all points on the closed fracture except for the start and end points;

[0098] S5: Using the tilt angle recovery formula, rotate each open crack counterclockwise around its starting point by the corresponding angle to restore it to the same tilt angle as the corresponding straight line segment in step S1; the tilt angle of the closed rough open crack is the angle between the line connecting its starting point and ending point and the X-axis.

[0099] S6: Preserve the geometric features of the open crack and use mesh generation software to obtain the final mesh containing the coarse open crack.

[0100] Further optimization is made in step S1, where the geometric parameters of the cracks include the number of cracks, their location distribution, length distribution, width distribution, and the number and dip angle of the cracks.

[0101] In the statistical distribution of fracture parameters, the fracture location distribution is set to a relatively random distribution;

[0102] The dip angle β of all cracks can be set to a range or a fixed value, between 0° and 90°;

[0103] Assume that the length values ​​of all cracks follow a log-normal distribution, and that the probability density of their lengths satisfies the following formula:

[0104]

[0105] Where L is the length of the crack, σ1 is the standard deviation of the length, and the mean length of the crack is calculated to be... μ1 is the mean of lnL;

[0106] Assume that the width values ​​of all cracks follow a Gaussian distribution, and the probability density formula for its width distribution is as follows:

[0107]

[0108] Where W is the width of the crack, σ2 is the standard deviation of the width, and the mean of the width is μ2.

[0109] Further optimization, based on the above statistical distribution patterns, yields the following steps for generating straight, closed cracks:

[0110] S1.1: Set the size boundaries of the mesh model, including the length and width of the entire model;

[0111] S1.2: Randomly select a point inside the model as the midpoint of the straight closed crack. Extend the crack in the opposite direction from the midpoint to both sides according to the set dip angle and length distribution law to obtain the start point and end point of the crack. Connect the start point and end point to form a straight line segment representing the crack.

[0112] S1.3: Determine whether the start and end points exceed the model boundaries:

[0113] If it does not exceed the limit, proceed to step S1.4;

[0114] If it exceeds the boundary, the straight line segment is shifted inwards towards the model boundary to ensure that the crack is within the model boundary.

[0115] S1.4: Calculate the distance Δd between the straight line segment and the cracks that have already formed inside the model. i And determine Δd i Is it less than the set distance d? min If the distance is less than d, move the line segment until the distance between the line segment and all other existing fractures is greater than or equal to d. min ;

[0116] S1.5: Repeat S1.2-1.4 until the set number of cracks are generated.

[0117] Further optimization, the set distance d min The set quantity is 10% of the average length of the crack.

[0118] Further optimization, step S2 specifically includes the following steps:

[0119] S2.1: Take two points on the straight line segment representing the crack, such that the midpoint and these two points divide the straight line segment into four equal parts. These two points are denoted as the first quarter point and the second quarter point, respectively.

[0120] Setting (x) s ,y s ), (x m ,y m ), (x e ,y e (x) represents the coordinates of the start point, midpoint, and end point of the fracture, respectively. q1 ,y q1 ) and (x q2 ,y q2 Let be the coordinates of the first and second quarter points, respectively.

[0121] x q1 =(x s +x m ) / 2,y q1 =(y s +ym ) / 2 (2-1)

[0122] x q2 =(x m +x e ) / 2,y q2 =(y m +y e ) / 2 (2-2)

[0123] S2.2: Using the first quarter point and the second quarter point as the center, set two intervals on the crack, with the length of each interval being 20% ​​of the crack length, and select a point from each interval;

[0124] S2.3: Move one of the points randomly to one side of the line segment by a certain distance, and denote it as the first fixed point; move the other point to the other side of the line segment by a certain distance, and denote it as the second fixed point;

[0125] Connect the starting point, the first fixed point, the second fixed point, and the ending point in sequence to form a three-segment line;

[0126] S2.4: Rotate the resulting three line segments clockwise around the starting point until the inclination angle of the three line segments is 0°, that is, the line connecting the starting and ending points of the three line segments is parallel to the X-axis; the rotation formula is as follows:

[0127]

[0128] Among them, (x i ,y i Let (i) be the coordinates of the i-th point on the three segments before rotation. When i = 1, it is the starting point (x). s ,y s ), i = n, which is the endpoint (x e ,y e );

[0129] (x j ,y j Let (x1, y1) be the j-th point on the three segments after rotation, where 1 ≤ j ≤ n. When j = 1, it is the starting point (x1, y1); when j = n, it is the ending point (x1, y1). n ,y n );

[0130] β is the dip angle of the fracture.

[0131] In further optimization, in step S2.4, the distances the two points move can be the same or different, and the moving distance is 5%-10% of the crack length.

[0132] Further optimization involves setting the vertical scaling factor and the number of iterations in step S3, and generating a coarse closed crack using the fractal iteration method as follows:

[0133] S3.1: After rotation, the points {(x) on the three segments are rotated. j ,y j )} is used as the initial set of interpolation points, and a fractal iteration is performed, x1 <x2<…<x j <… <x n-1 <x n Points k and x generated based on the fractal iteration method j <x k <x j+1 Its coordinates (x k ,y k The following formula can be used to calculate:

[0134]

[0135] Among them, a j ,c j ,e j , and f j These are the variables in the fractal iteration, and their respective calculation formulas are as follows:

[0136] a j =(x j+1 -x j ) / (x n -x1) (3-2)

[0137] c j =[(y j+1 -y j )-d×(y n -y1)] / (x n -x1) (3-3)

[0138] e j =(x n ×x j -x1×x j+1 ) / (x n -x1) (3-4)

[0139]

[0140] As can be seen from the above formula, if the crack is a vertical line, it only has a start point and an end point, i.e., x. j+1 =x n x j =x1, resulting in a j =1,e j =0, then x k =a j *x j +e j =x1, which cannot satisfy x j <x k <xj+1 This leads to interpolation failure. Therefore, this invention first transforms a straight line into a three-segment line. As the inclination angle approaches 90°, i.e., x... n -x1 approaches 0, causing c j and f j Approaching infinity will also cause the fractal iteration to fail. This is why this invention needs to rotate its tilt angle to 0°. d represents the fractal iteration matrix W. j The vertical scaling factor is set to 0.25, which results in a rougher curve that is more in line with reality and is the preferred value in this invention.

[0141] The fractal iteration method has wide applications in geological engineering, simulating complex rock and soil structures. Existing methods can generate coarse closed fractures, a significant improvement over traditional straight-line closed fractures, and can meet the needs of most coarse closed fracture applications in numerical simulation engineering. However, open fractures are formed under geological disturbances and are prone to high dip angles, which the fractal iteration method cannot handle. The improved fractal iteration method in this invention can handle straight lines and curves with any dip angle, facilitating the subsequent generation of open fractures.

[0142] S3.2: Using the points on the curve after the iteration in step S3.1 as the initial set of interpolation points, repeat the above steps to perform a second fractal iteration. The curve after the fractal iteration forms a rough closed crack.

[0143] The higher the number of iterations, the smoother the curve; however, the number of points also increases dramatically with the number of processing iterations (T). For a three-segment line, the number of points is 82 after two iterations and 730 after four iterations. However, the difference in curve appearance between the two and four iterations is not very significant, and the increased number of points consumes a lot of memory and performance. Therefore, the curve after two iterations is sufficient to meet the requirements for curve smoothness.

[0144] Further optimization: In step S4, the mean distance of movement for each point other than the starting point and the ending point is μ1 / 2, and the standard deviation is σ1 / 2; at this time, the width distribution of the opening crack follows the probability density formula of the width distribution in step S1, i.e., formula (1-2).

[0145] Further optimization involves restoring the dip angle of the open fracture in step S5 by rotating all points on the open fracture counterclockwise by β around the starting point, as shown in the following formula:

[0146]

[0147] Among them, (x mi ,y mi ) and (xfi ,y fi The points are the points on the open fracture with an initial dip angle of 0° and the points on the final open fracture after the dip angle β is restored.

[0148] Further optimization involves the following step S6: after preserving the geometric features of the opening cracks, the mesh is divided as follows: all edge curves of the opening cracks and the model boundary are set as the boundaries of the mesh model, and meshing is performed; that is, the area where the opening cracks intersect with the model boundary forms a mesh.

[0149] Reference Figure 13 , Figure 13 This is a schematic diagram of the structure of a rock mass rough opening fracture mesh generation device based on the fractal iteration method, which is part of the hardware operating environment of the embodiment of the present invention.

[0150] like Figure 13 As shown, the rock mass rough opening fracture mesh generation device based on the fractal iteration method may include: a processor 1001, such as a central processing unit (CPU), a communication bus 1002, a user interface 1003, a network interface 1004, and a memory 1005. The communication bus 1002 is used to enable communication between these components. The user interface 1003 may include a display screen or an input unit such as a keyboard; optionally, the user interface 1003 may also include a standard wired interface or a wireless interface. The network interface 1004 may optionally include a standard wired interface or a wireless interface (such as a Wi-Fi interface). The memory 1005 may be a high-speed random access memory (RAM) or a stable non-volatile memory (NVM), such as a disk drive. The memory 1005 may also optionally be a storage device independent of the aforementioned processor 1001.

[0151] Those skilled in the art will understand that Figure 13 The structure shown does not constitute a limitation on the rock mass rough opening fracture mesh generation device based on the fractal iteration method, and may include more or fewer components than shown, or combine certain components, or have different component arrangements.

[0152] like Figure 13 As shown, the memory 1005, which serves as a storage medium, may include an operating system, a data storage module, a network communication module, a user interface module, and a rock mass rough opening fracture mesh generation program based on the fractal iteration method.

[0153] exist Figure 13In the rock mass rough opening fracture mesh generation device based on the fractal iteration method shown, the network interface 1004 is mainly used for data communication with the network server; the user interface 1003 is mainly used for data interaction with the user; the processor 1001 and memory 1005 in the rock mass rough opening fracture mesh generation device based on the fractal iteration method of the present invention can be set in the rock mass rough opening fracture mesh generation device based on the fractal iteration method. The rock mass rough opening fracture mesh generation device based on the fractal iteration method calls the rock mass rough opening fracture mesh generation program based on the fractal iteration method stored in the memory 1005 through the processor 1001, and executes the rock mass rough opening fracture mesh generation method based on the fractal iteration method provided in the embodiment of the present invention.

[0154] Example

[0155] The method for generating rough open fracture meshes in rock mass based on the fractal iteration method provided in this invention includes the following steps:

[0156] S1: Establish a two-dimensional rectangular coordinate system XOY, and generate a two-dimensional straight closed fracture model based on the set fracture geometric parameters and statistical distribution law. This straight closed fracture model includes multiple straight line segments representing fractures.

[0157] S2: By randomly selecting points near the quarter point and vertically translating them, each straight line segment is transformed into a zigzag three-segment line, and all three-segment lines are rotated clockwise to 0°, that is, the line connecting the start and end points of the three-segment lines is parallel to the X-axis;

[0158] S3: Set the vertical scaling factor and the number of iterations, and use the fractal iteration method to generate a rough closed crack for each rotated three-segment line;

[0159] S4: Move each point on each closed fracture, except for the start and end points, randomly a certain distance in the positive direction of the Y-axis, and record the moved point as the ascending point; then move each point on each closed fracture, except for the start and end points, in the negative direction of the Y-axis by the same distance as the positive direction of the Y-axis, and record the moved point as the descending point; connect the start, ascending, end, and descending points in sequence to form an open fracture, and delete all points on the closed fracture except for the start and end points;

[0160] S5: Using the tilt angle recovery formula, rotate each open crack counterclockwise around its starting point by the corresponding angle to restore it to the same tilt angle as the corresponding straight line segment in step S1; the tilt angle of the closed rough open crack is the angle between the line connecting its starting point and ending point and the X-axis.

[0161] S6: Preserve the geometric features of the open crack and use mesh generation software to obtain the final mesh containing the coarse open crack.

[0162] Further optimization is made in step S1, where the geometric parameters of the cracks include the number of cracks, their location distribution, length distribution, width distribution, and the number and dip angle of the cracks.

[0163] In the statistical distribution of fracture parameters, the fracture location distribution is set to a relatively random distribution;

[0164] The dip angle β of all cracks can be set to a range or a fixed value, between 0° and 90°;

[0165] Assume that the length values ​​of all cracks follow a log-normal distribution, and that the probability density of their lengths satisfies the following formula:

[0166]

[0167] Where L is the length of the crack, σ1 is the standard deviation of the length, and the mean length of the crack is calculated to be... μ1 is the mean of lnL;

[0168] Assume that the width values ​​of all cracks follow a Gaussian distribution, and the probability density formula for its width distribution is as follows:

[0169]

[0170] Where W is the width of the crack, σ2 is the standard deviation of the width, and the mean of the width is μ2.

[0171] Further optimization, based on the above statistical distribution patterns, yields the following steps for generating straight, closed cracks:

[0172] S1.1: Define the size boundaries of the mesh model, including the length and width of the entire model;

[0173] S1.2: Randomly select a point inside the model as the midpoint of the straight closed crack. Extend the crack in the opposite direction from the midpoint to both sides according to the set dip angle and length distribution law to obtain the start point and end point of the crack. Connect the start point and end point to form a straight line segment representing the crack.

[0174] S1.3: Determine whether the start and end points exceed the model boundaries:

[0175] If it does not exceed the limit, proceed to step S1.4;

[0176] If it exceeds the boundary, the straight line segment is shifted inwards towards the model boundary to ensure that the crack is within the model boundary.

[0177] S1.4: Calculate the distance Δd between the straight line segment and the cracks that have already formed inside the model. i And determine Δd i Is it less than the set distance d? minIf the distance is less than d, move the line segment until the distance between the line segment and all other existing fractures is greater than or equal to d. min ;

[0178] S1.5: Repeat S1.2-1.4 until the set number of cracks are generated.

[0179] Further optimization, the set distance d min The set quantity is 10% of the average length of the crack.

[0180] Further optimization, step S2 specifically includes the following steps:

[0181] S2.1: Take two points on the straight line segment representing the crack, such that the midpoint and these two points divide the straight line segment into four equal parts. These two points are denoted as the first quarter point and the second quarter point, respectively.

[0182] Setting (x) s ,y s ), (x m ,y m ), (x e ,y e (x) represents the coordinates of the start point, midpoint, and end point of the fracture, respectively. q1 ,y q1 ) and (x q2 ,y q2 Let be the coordinates of the first and second quarter points, respectively.

[0183] x q1 =(x s +x m ) / 2,y q1 =(y s +y m ) / 2 (2-1)

[0184] x q2 =(x m +x e ) / 2,y q2 =(y m +y e ) / 2 (2-2)

[0185] S2.2: Using the first quarter point and the second quarter point as the center, set two intervals on the crack, with the length of each interval being 20% ​​of the crack length, and select a point from each interval;

[0186] S2.3: Move one of the points randomly to one side of the line segment by a certain distance, and denote it as the first fixed point; move the other point to the other side of the line segment by a certain distance, and denote it as the second fixed point;

[0187] Connect the starting point, the first fixed point, the second fixed point, and the ending point in sequence to form a three-segment line;

[0188] S2.4: Rotate the resulting three line segments clockwise around the starting point until the inclination angle of the three line segments is 0°, that is, the line connecting the starting and ending points of the three line segments is parallel to the X-axis; the rotation formula is as follows:

[0189]

[0190] Among them, (x i ,y i Let (i) be the coordinates of the i-th point on the three segments before rotation. When i = 1, it is the starting point (x). s ,y s ), i = n, which is the endpoint (x e ,y e );

[0191] (x j ,y j Let (x1, y1) be the j-th point on the three segments after rotation, where 1 ≤ j ≤ n. When j = 1, it is the starting point (x1, y1); when j = n, it is the ending point (x1, y1). n ,x n );

[0192] β is the dip angle of the fracture.

[0193] In further optimization, in step S2.4, the distances the two points move can be the same or different, and the moving distance is 5%-10% of the crack length.

[0194] Further optimization involves setting the vertical scaling factor and the number of iterations in step S3, and generating a coarse closed crack using the fractal iteration method as follows:

[0195] S3.1: After rotation, the points {(x) on the three segments are rotated. j ,y j )} is used as the initial set of interpolation points, and a fractal iteration is performed, x1 <x2<…<x j <… <x n-1 <x n Points k and x generated based on the fractal iteration method j <x k <x j+1 Its coordinates (x k ,y k The following formula can be used to calculate:

[0196]

[0197] Among them, a j ,c j ,e j , and fj These are the variables in the fractal iteration, and their respective calculation formulas are as follows:

[0198] a j =(x j+1 -x j ) / (x n -x1) (3-2)

[0199] c j =[(y j+1 -y j )-d×(y n -y1)] / (x n -x1) (3-3)

[0200] e j =(x n ×x j -x1×x j+1 ) / (x n -x1) (3-4)

[0201]

[0202] As can be seen from the above formula, if the crack is a vertical line, it only has a start point and an end point, i.e., x. j+1 =x n x j =x1, resulting in a j =1,e j =0, then x k =a j *x j +e j =x1, which cannot satisfy x j <x k <x j+1 This leads to interpolation failure. Therefore, this invention first transforms a straight line into a three-segment line. As the inclination angle approaches 90°, i.e., x... n -x1 approaches 0, causing c j and f j Approaching infinity will also cause the fractal iteration to fail. This is why this invention needs to rotate its tilt angle to 0°. d represents the fractal iteration matrix W. j The vertical scaling factor is set to 0.25, which results in a rougher curve that is more in line with reality and is the preferred value in this invention.

[0203] The fractal iteration method has wide applications in geological engineering, and can be used to simulate the complex structures of rocks and soils. For example, Gao Jie et al. used this method to generate discrete fracture networks (see Chinese patent: "A Method for Generating Discrete Fracture Networks Based on Iterative Function Systems," application number: CN202211146540.1). This method can already generate coarse closed fractures, a significant improvement over traditional straight-line closed fractures, and can meet the application requirements of most coarse closed fractures in numerical simulation engineering. However, open fractures are formed under geological disturbances and are prone to high dip angles, which the fractal iteration method cannot handle. The improved fractal iteration method in this invention can handle straight lines and curves with any dip angle, facilitating the subsequent generation of open fractures.

[0204] S3.2: Using the points on the curve after the iteration in step S3.1 as the initial set of interpolation points, repeat the above steps to perform a second fractal iteration. The curve after the fractal iteration forms a rough closed crack.

[0205] The higher the number of iterations, the smoother the curve; however, the number of points also increases dramatically with the number of processing iterations (T). For a three-segment line, the number of points is 82 after two iterations and 730 after four iterations. However, the difference in curve appearance between the two and four iterations is not very significant, and the increased number of points consumes a lot of memory and performance. Therefore, the curve after two iterations is sufficient to meet the requirements for curve smoothness.

[0206] Further optimization: In step S4, the mean distance of movement for each point other than the starting point and the ending point is μ1 / 2, and the standard deviation is σ1 / 2; at this time, the width distribution of the opening crack follows the probability density formula of the width distribution in step S1, i.e., formula (1-2).

[0207] Further optimization involves restoring the dip angle of the open fracture in step S5 by rotating all points on the open fracture counterclockwise by β around the starting point, as shown in the following formula:

[0208]

[0209] Among them, (x mi ,y mi ) and (x fi ,y fi The points are the points on the open fracture with an initial dip angle of 0° and the points on the final open fracture after the dip angle β is restored.

[0210] Further optimization involves the following step S6: after preserving the geometric features of the opening cracks, the mesh is divided as follows: all edge curves of the opening cracks and the model boundary are set as the boundaries of the mesh model, and meshing is performed; that is, the area where the opening cracks intersect with the model boundary forms a mesh.

[0211] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments as well as all changes and modifications falling within the scope of the invention.

[0212] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of the claims of this invention and their equivalents, this invention also intends to include these modifications and variations.

Claims

1. A method for generating rough open fracture meshes in rock mass based on the fractal iteration method, characterized in that, Includes the following steps: S1: Establish a two-dimensional rectangular coordinate system XOY, and generate a two-dimensional straight closed fracture model based on the set fracture geometric parameters and statistical distribution law. This straight closed fracture model includes multiple straight line segments representing fractures. S2: By randomly selecting points near the quarter point and vertically translating them, each straight line segment is transformed into a zigzag three-segment line, and all three-segment lines are rotated clockwise to 0°, that is, the line connecting the start and end points of the three-segment lines is parallel to the X-axis; S3: Set the vertical scaling factor and the number of iterations, and use the fractal iteration method to generate a rough closed crack for each rotated three-segment line; S4: Move each point on each closed fracture, except for the start and end points, randomly a certain distance in the positive direction of the Y-axis, and record the moved point as the ascending point; then move each point on each closed fracture, except for the start and end points, in the negative direction of the Y-axis by the same distance as the positive direction of the Y-axis, and record the moved point as the descending point; connect the start, ascending, end, and descending points in sequence to form an open fracture, and delete all points on the closed fracture except for the start and end points; S5: Using the tilt angle recovery formula, rotate each open crack counterclockwise around its starting point by the corresponding angle to restore it to the same tilt angle as the corresponding straight line segment in step S1; the tilt angle of the closed rough open crack is the angle between the line connecting its starting point and ending point and the X-axis. S6: Preserve the geometric features of the open crack and use mesh generation software to obtain the final mesh containing the coarse open crack.

2. The method for generating rough open fracture meshes in rock mass based on the fractal iteration method according to claim 1, characterized in that, In step S1, the geometric parameters of the cracks include the number of cracks, their location distribution, length distribution, width distribution, number of cracks, and inclination angle. In the statistical distribution of fracture parameters, the fracture location distribution is set to a relatively random distribution; The dip angle β of all cracks can be set to a range or a fixed value, between 0° and 90°; Assume that the length values ​​of all cracks follow a log-normal distribution, and that the probability density of their lengths satisfies the following formula: Where L is the length of the crack, lnL is the natural logarithm of the length (i.e., lnL follows a normal distribution); σ1 is the standard deviation of the length lnL, and μ1 is the mean of lnL, calculated using an integral formula. The mean crack length was obtained as follows: Assume that the width values ​​of all cracks follow a Gaussian distribution, and the probability density formula for its width distribution is as follows: Where W is the width of the crack, σ2 is the standard deviation of the width, and the mean of the width is μ2.

3. The method for generating rough open fracture meshes in rock mass based on the fractal iteration method according to claim 1, characterized in that, Based on the statistical distribution pattern in S1, the steps for generating a straight closed fracture are as follows: S1.1: Define the size boundaries of the mesh model, including the length and width of the entire model; S1.2: Randomly select a point inside the model as the midpoint of the straight closed crack. Extend the crack in the opposite direction from the midpoint to both sides according to the set dip angle and length distribution law to obtain the start point and end point of the crack. Connect the start point and end point to form a straight line segment representing the crack. S1.3: Determine whether the start and end points exceed the model boundaries: If it does not exceed the limit, proceed to step S1.4; If it exceeds the boundary, the straight line segment is shifted inwards towards the model boundary to ensure that the crack is within the model boundary. S1.4: Calculate the distance Δd between the straight line segment and the cracks that have already formed inside the model. i And determine Δd i Is it less than the set distance d? min If the distance is less than d, move the line segment until the distance between the line segment and all other existing fractures is greater than or equal to d. min ; S1.5: Repeat S1.2-1.4 until the set number of cracks are generated.

4. The method for generating rough open fracture meshes in rock mass based on the fractal iteration method according to claim 3, characterized in that, The set distance d in S1.4 min The set quantity is 10% of the average length of the crack.

5. The method for generating rough open fracture meshes in rock mass based on the fractal iteration method according to claim 1, characterized in that, Step S2 specifically includes the following steps: S2.1: Take two points on the straight line segment representing the crack, such that the midpoint and these two points divide the straight line segment into four equal parts. These two points are denoted as the first quarter point and the second quarter point, respectively. Setting (x) s ,y s ), (x m ,y m ), (x e ,y e (x) represents the coordinates of the start point, midpoint, and end point of the fracture, respectively. q1 ,y q1 ) and (x q2 ,y q2 Let be the coordinates of the first and second quarter points, respectively. x q1 =(x s +x m ) / 2,y q1 =(and s +and m ) / 2 (2-1) x q2 =(x m +x e ) / 2,y q2 =(and m +and e ) / 2 (2-2) S2.2: Using the first quarter point and the second quarter point as the center, set two intervals on the crack, with the length of each interval being 20% ​​of the crack length, and select a point from each interval; S2.3: Move one of the points randomly to one side of the line segment by a certain distance, and denote it as the first fixed point; move the other point to the other side of the line segment by a certain distance, and denote it as the second fixed point; Connect the starting point, the first fixed point, the second fixed point, and the ending point in sequence to form a three-segment line; S2.4: Rotate the resulting three line segments clockwise around the starting point until the inclination angle of the three line segments is 0°, that is, the line connecting the starting and ending points of the three line segments is parallel to the X-axis; the rotation formula is as follows: Among them, (x i ,y i Let (i) be the coordinates of the i-th point on the three segments before rotation. When i = 1, it is the starting point (x). s ,y s ), i = n, which is the endpoint (x e ,y e ); (x j ,y j Let (x1, y1) be the j-th point on the three segments after rotation, where 1 ≤ j ≤ n. When j = 1, it is the starting point (x1, y1); when j = n, it is the ending point (x1, y1). n ,y n ); β is the dip angle of the fracture.

6. The method for generating rough open fracture meshes in rock mass based on the fractal iteration method according to claim 5, characterized in that, In step S2.4, the distances the two points move can be the same or different, and the moving distance is 5%-10% of the crack length.

7. The method for generating rough open fracture meshes in rock mass based on the fractal iteration method according to claim 1, characterized in that, In step S3, the steps for setting the vertical scaling factor and the number of iterations, and generating a rough closed crack using the fractal iteration method are as follows: S3.1: After rotation, the points {(x) on the three segments are rotated. j ,y j )} is used as the initial set of interpolation points, and a fractal iteration is performed, x1 <x2<…<x j <… <x n-1 <x n Points k and x generated based on the fractal iteration method j <x k <x j+1 Its coordinates (x k ,y k The following formula can be used to calculate: Among them, a j ,c j ,e j , and f j These are the variables in the fractal iteration, and their respective calculation formulas are as follows: has j =(x j+1 -x j ) / (x n -x1) (3-2) c j =[(and j+1 -and j )-d×(y n -y1)] / (x n -x1) (3-3) And j =(x n ×x j -x1×x j+1 ) / (x n -x1) (3-4) f j <[x n ×y j -x1×y j+1 -d×(x n ×y1-x1× (3-5)y n )] / (x n -x1) S3.2: Using the points on the curve after step S3.1 iteration as the initial set of interpolation points, repeat the above steps to perform secondary fractal iteration; the curve after fractal iteration forms a rough closed crack. Preferably, in step S4, the mean distance of each point except the starting point and the ending point is μ1 / 2 and the standard deviation is σ1 / 2; at this time, the width distribution of the opening crack follows the probability density formula of the width distribution in step S1, i.e. formula (1-2). Preferably, in step S5, the process of restoring the inclination angle of the open fracture is achieved by rotating all points on the open fracture counterclockwise by β around the starting point, as shown in the following formula: Among them, (x mi ,y mi ) and (x fi ,y fi Points on the open fracture with an initial dip angle of 0° and points on the final open fracture after the dip angle β is restored, respectively. Preferably, in step S6, after preserving the geometric features of the opening cracks, the mesh is divided as follows: all the edge curves of the opening cracks and the model boundary are set as the boundaries of the mesh model, and the mesh is split; that is, the area where the opening cracks intersect with the model boundary is formed into a mesh.

8. A device for generating rough, open-mouth fracture grids in rock mass based on a fractal iteration method, characterized in that, include: The two-dimensional straight closed fracture model generation module is used to establish a two-dimensional rectangular coordinate system XOY and generate a two-dimensional straight closed fracture model based on the set fracture geometric parameters and statistical distribution law. The straight closed fracture model includes multiple straight line segments representing the fracture. The line segment conversion module is used to convert each straight line segment into a zigzag three-segment line by vertically translating a randomly selected point near the quarter point, and then rotating all three-segment lines clockwise to 0°, that is, the line connecting the start and end points of the three-segment lines is parallel to the X-axis. The coarse closed-slit generation module is used to set the vertical scaling factor and the number of iterations. It uses the fractal iteration method to generate coarse closed-slits for each rotated tri-segment line. The open fracture forming module is used to randomly move each point on each closed fracture, except for the start and end points, a certain distance in the positive direction of the Y-axis, and record the moved points as the upward points; then, each point, except for the start and end points, is moved in the negative direction of the Y-axis by the same distance as the positive direction of the Y-axis, and the point after this movement is recorded as the downward point; the start point, upward point, end point, and downward point are connected in sequence to form an open fracture, and all points on the closed fracture, except for the start and end points, are deleted; An angle rotation module is used to rotate each open crack counterclockwise around its starting point by a corresponding angle using the tilt angle recovery formula, so that it is restored to the same tilt angle as the corresponding straight line segment in step S1; the tilt angle of the closed rough open crack is the angle between the line connecting its starting point and ending point and the X-axis; The crack mesh generation module is used to preserve the geometric features of open cracks and to obtain the final mesh containing coarse open cracks using mesh generation software.

9. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a rock mass rough opening fracture mesh generation program based on the fractal iteration method. When the rock mass rough opening fracture mesh generation program based on the fractal iteration method is executed by a processor, it implements the steps of the rock mass rough opening fracture mesh generation method based on the fractal iteration method as described in any one of claims 1-7.

10. An electronic device, characterized in that, The device includes a memory and a processor. The memory stores a program for generating rough open fracture meshes in rock mass based on the fractal iteration method. When the program is executed by the processor, it implements the steps of the method for generating rough open fracture meshes in rock mass based on the fractal iteration method as described in any one of claims 1-7.

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