A method for simulating direct shear numerical tests on real rock mass structural surfaces

Abstract

The present application proposes a method for simulating direct shear numerical tests on the real structural surface of a rock mass, in the field of rock mechanics technology, including: obtaining a standard rock sample; preparing artificial cracks on the standard rock sample by Brazilian splitting; scanning the surface of the artificial cracks using three-dimensional scanning technology to obtain point cloud data of the real structural surface of the rock mass; establishing a geometric numerical model of the direct shear test on the real structural surface of the rock mass based on the point cloud data; establishing a control equation group considering the wear of the real structural surface of the rock mass according to the geometric numerical model of the direct shear test on the real structural surface of the rock mass; and realizing numerical simulation of the direct shear test on the real structural surface of the rock mass considering the wear according to the control equation group. The method of the present application lays a solid foundation for accurately understanding and scientifically mastering the research on the shear mechanics response and wear evolution law of the real structural surface of the rock mass, and improves the accuracy.

Description

Technical Field

[0001] The invention belongs to the technical field of rock mechanics, and in particular relates to a direct shear numerical test simulation method for a real structural surface of a rock mass. Background Art

[0002] The shear properties of rock joints are of great significance in studying the hydraulic properties of rock masses. Their shear behavior is affected by a variety of complex phenomena, including expansion, deformation, contact, and wear. Therefore, accurate prediction of the shear properties of rock joints is crucial to understanding the seepage path and solute migration during the shear process.

[0003] Existing studies have shown that geological and engineering actions can cause shear behavior on rock mass structural surfaces, and the shear properties of rock joints are mainly controlled by the mechanical properties of the rock mass, the geometric characteristics of the joints, and the applied stress conditions. However, traditional direct shear tests can only provide quantitative data results of rock joints, such as peak shear strength and residual shear strength, and cannot directly observe the contact and wear between joints during the shear process, which to a certain extent limits the in-depth summary of the failure laws of rock joints.

[0004] Numerical simulation methods provide an effective means to overcome the above limitations. In the past, numerical simulations of rock joint shear performance usually used geometric approximation to simplify the contact area between joints to a very small distance in order to simplify the calculation. However, this method is difficult to accurately simulate the friction and wear evolution of joints, and the peak and residual shear strengths obtained by geometric approximation often lack sufficient accuracy.

[0005] So far, no research has focused on the implementation of direct shear numerical tests on real structural surfaces of rock masses taking into account geological and engineering effects. Summary of the invention

[0006] In view of the shortcomings of the prior art, this application proposes a method for simulating direct shear numerical tests on real rock mass structural surfaces, including:

[0007] Obtain standard rock samples;

[0008] On the standard rock sample, artificial fractures are prepared by Brazilian splitting;

[0009] The surface of artificial fractures is scanned using 3D scanning technology to obtain point cloud data of the real structural surface of the rock mass;

[0010] Establishing a direct shear test geometric numerical model of the real structural surface of the rock mass based on the point cloud data;

[0011] According to the geometric numerical model of the direct shear test of the real structural surface of the rock mass, a control equation group considering the wear of the real structural surface of the rock mass is established;

[0012] The numerical simulation of direct shear test on real structural surface of rock mass considering wear is realized according to the control equations.

[0013] The three-dimensional scanning technology is used to scan the surface of the artificial fracture to obtain point cloud data of the real structural surface of the rock mass, including:

[0014] The surface of artificial fractures is scanned using 3D scanning technology to obtain point cloud data of the real structural surface of the rock mass;

[0015] Performing noise reduction processing on the point cloud data to obtain noise-reduced point cloud data;

[0016] The denoised point cloud data is subjected to coordinate system transformation to obtain point cloud data of the upper structural surface and point cloud data of the lower structural surface;

[0017] Place the point cloud data of the upper structural surface and the point cloud data of the lower structural surface in the same coordinate system;

[0018] The point cloud data in the same coordinate system is meshed to obtain meshed point cloud data.

[0019] The direct shear test geometric numerical model of the real structural surface of the rock mass is established based on the point cloud data, including:

[0020] A cube is used to simulate a standard rock sample;

[0021] Based on the simulated standard rock specimens, the gridded point cloud data is used as a parameterized surface to generate a direct shear test geometric numerical model of the real structural surface of the rock mass.

[0022] The method of realizing the numerical simulation of the direct shear test of the real structural surface of the rock mass considering the wear according to the control equation group includes:

[0023] Under the condition of considering wear, the material properties are assigned and boundary conditions are imposed in the direct shear test geometric numerical model of the real structural surface of the rock mass, and the direct shear test geometric numerical model of the real structural surface of the rock mass is meshed;

[0024] According to the control equations, the meshed direct shear test geometric numerical model is numerically simulated.

[0025] The control equation group includes: local friction force on the contact unit, total potential energy, apparent inclination angle, yield force of the contact unit, roughness angle, total shear force, normal displacement during shearing, normal force, total number of contact points, total wear area and wear law.

[0026] According to the control equations, the direct shear test geometric numerical model after meshing is numerically simulated, including:

[0027] Step S6.2.1: Construct an elastic-plastic contact model based on the total potential energy and the apparent inclination angle;

[0028] Step S6.2.2: Calculate the normal stress distribution according to the elastic-plastic contact model and determine the contact unit;

[0029] Step S6.2.3: Calculate the roughness angles of all contact elements according to the normal stress distribution, and find the maximum values ​​of all roughness angles;

[0030] Step S6.2.4: Calculate the local friction force on the contact element and the yield force of the contact element;

[0031] Step S6.2.5: Calculate the total wear area of ​​the micro-asperities when the yield force of the contact element is greater than the local friction force on the contact element;

[0032] Step S6.2.6: When the yield force of the contact unit is less than or equal to the local friction force on the contact unit, the heights of the upper structural surface and the lower structural surface are modified by using the maximum value of the roughness angle, and the modified heights of the upper structural surface and the lower structural surface are substituted into the elastic-plastic contact model, and return to step S6.2.1;

[0033] Step S6.2.7: Calculate the shear stress distribution based on the local friction force on the contact unit, and calculate the wear distribution based on the normal stress distribution to achieve numerical simulation of the direct shear test geometric numerical model after meshing.

[0034] According to the total potential energy and apparent inclination angle, an elastic-plastic contact model is constructed, and the calculation formula is as follows:

[0035] ;

[0036] in, is the total potential energy, Area is the area of ​​the contact surface, is the normal stress, is the normal displacement of the upper and lower surfaces in the contact area Area, is the total prescribed displacement of the two contact surfaces in the contact region based on the geometric interference assumption, is the composite incremental surface displacement in the plastic deformation zone where the contact stress reaches the rock hardness H, σ n >H, H is a parameter describing the rock's resistance to inelastic deformation, is the incremental displacement of the two contact surfaces until the contact stress reaches the rock hardness, is the unit normal vector, is the unit vector in the shear direction.

[0037] According to the normal stress distribution, the roughness angle of all contact elements is calculated as follows:

[0038] ;

[0039] in, is the target roughness angle, f y is the yield force of the contact element, A is the area of ​​the contact element, σ n is the local normal stress of the contact element, is the basic friction angle of standard rock sample.

[0040] The local friction force on the contact unit is calculated as follows:

[0041] ;

[0042] ;

[0043] Where A is the area of ​​the contact unit, σ ni is the local normal stress of contact element i, is the basic friction angle of the standard rock sample, θ r is the local roughness angle of contact element i, is the local friction force on contact element i, is the shear step;

[0044] The yield force of the contact unit is calculated as follows:

[0045] ;

[0046] Among them, f yi is the yield force of contact unit i, c is the cohesive force of the standard rock specimen, is the friction angle of the standard rock sample, A is the area of ​​the contact unit, σ ni is the local normal stress of contact element i;

[0047] The total wear area is calculated as follows:

[0048] ;

[0049] Where G is the total wear area, σ n is the local normal stress of the contact unit, k is the probability of wear particle formation, N is the total number of contact points along the path x, D is the average diameter of m contact units i, F N is the normal force.

[0050] The shear stress distribution is calculated based on the local friction force on the contact unit, and the wear distribution is calculated based on the normal stress distribution. The calculation formula is as follows:

[0051] ;

[0052] ;

[0053] in, is the shear stress of contact element i, is the wear of contact unit i, is the local friction force on contact element i, A t is the projection area of ​​the structural surface on the xy plane, that is , where L x is the length of the standard rock sample, L y is the standard rock sample width, F N is the normal force, σ ni is the local normal stress of contact element i, and x is the path.

[0054] Beneficial effects:

[0055] This application proposes a method for simulating direct shear numerical tests on the real structural surface of rock mass. Based on Mohr-Coulomb's law, friction law and wear law, the control equation of the direct shear process of rock specimens taking into account the wear of the real structural surface of rock mass is established. The advantage is that the contact area is refined into a micro-convex body composed of several contact units, and the normal stress of the contact area is calculated based on contact mechanics. Specifically, a high-precision elastic-plastic contact model is used to calculate a more realistic normal stress distribution and surface wear deformation in each shear step. The method of this application has laid a solid foundation for accurately understanding and scientifically mastering the research on the shear mechanics response and wear evolution law of the real structural surface of rock mass. This method has high accuracy, good practical effect and wide applicability. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 A flow chart of a method for simulating a direct shear numerical test of a real structural surface of a rock mass according to an embodiment of the present invention;

[0057] Figure 2 A schematic flow chart of a method for simulating a direct shear numerical test of a real structural surface of a rock mass according to an embodiment of the present invention;

[0058] Figure 3 Schematic diagram of the rock sample geometric model considering the wear of the real structural surface of the rock mass according to the embodiment of the present application;

[0059] Figure 4 Schematic diagram of contact unit wear reduction calculation in an embodiment of the present application;

[0060] Figure 5 Schematic diagram of the intersection of the real structural surfaces of the rock mass in the embodiment of the present application, wherein (1) is a schematic diagram of the intersection of two micro-convex bodies in this embodiment; (2) is a schematic diagram of the normal force of the contact between the two real structural surfaces of the rock mass in this embodiment;

[0061] Figure 6 Schematic diagrams of stress distribution and wear distribution obtained by solving the numerical simulation implementation method of the direct shear test of the rock structure surface considering wear in the embodiment of the present application, (1) schematic diagram of stress distribution, (2) schematic diagram of wear distribution. DETAILED DESCRIPTION

[0062] The specific implementation of the present application is further described in detail below in conjunction with the drawings and examples.

[0063] Example:

[0064] This embodiment proposes a method for simulating a direct shear numerical test of a real rock mass structure surface. Figure 1 , Figure 2 As shown, including:

[0065] Step S1: obtaining a standard rock sample;

[0066] Step S2: preparing artificial fractures on the standard rock sample by Brazilian splitting;

[0067] Step S3: Scan the surface of the artificial fracture using 3D scanning technology to obtain point cloud data of the real structural surface of the rock mass, including:

[0068] Step S3.1: Scan the surface of the artificial fracture using three-dimensional scanning technology to obtain point cloud data of the real structural surface of the rock mass;

[0069] Step S3.2: performing noise reduction processing on the point cloud data to obtain noise-reduced point cloud data;

[0070] Step S3.3: performing coordinate system transformation on the denoised point cloud data to obtain point cloud data of the upper structural surface and point cloud data of the lower structural surface;

[0071] Step S3.4: placing the point cloud data of the upper structural surface and the point cloud data of the lower structural surface in the same coordinate system;

[0072] Step S3.5: Grid the point cloud data in the same coordinate system to obtain gridded point cloud data.

[0073] In this embodiment, the standard rock sample is subjected to Brazilian splitting to obtain artificial rough cracks. Then, a three-dimensional laser scanner is used to scan the surface of the prepared artificial rough cracks to obtain point cloud data of the real structural surface of the rock mass, and the point cloud data is exported after noise reduction. The exported point cloud data is imported into Geomagic software for coordinate system transformation, so that the point cloud data of the upper and lower structural surfaces are placed in the same coordinate system. The point cloud data of the transformed coordinate system is imported into Surfer software for grid division, and is discretized into a structured square xy grid with a size of ∆x, so as to achieve uniform processing of the point cloud data.

[0074] Step S4: establishing a direct shear test geometric numerical model of the real structural surface of the rock mass based on the point cloud data, including:

[0075] Step S4.1: using a cube to simulate a standard rock sample;

[0076] Step S4.2: Based on the simulated standard rock specimen, the gridded point cloud data is used as a parameterized surface to generate a direct shear test geometric numerical model of the real structural surface of the rock mass.

[0077] In this embodiment, COMSOL Multiphysics software is used to build a cube to simulate a standard rock sample. The processed point cloud data is imported into COMSOL Multiphysics software as a parameterized surface to generate a rock sample geometric numerical model containing the real structural surface of the rock mass, such as Figure 3 shown.

[0078] Step S5: establishing a control equation group considering the wear of the real structural surface of the rock mass according to the geometric numerical model of the direct shear test of the real structural surface of the rock mass;

[0079] In this embodiment, the control equation group is a group of equations consisting of local friction force on the contact unit, total potential energy, apparent inclination angle, yield force of the contact unit, roughness angle, total shear force, normal displacement during shearing, normal force, total number of contact points, total wear area and wear law.

[0080] Step S6: Implement numerical simulation of direct shear test of real rock mass structure surface considering wear according to the control equations, such as Figure 2 As shown, including:

[0081] Step 6.1: Under the condition of considering wear, assign material properties and apply boundary conditions in the direct shear test geometric numerical model of the real structural surface of the rock mass, and mesh the direct shear test geometric numerical model of the real structural surface of the rock mass;

[0082] Step S6.2: According to the control equations, numerical simulation is performed on the meshed direct shear test geometric numerical model.

[0083] According to the control equations, the direct shear test geometric numerical model after meshing is numerically simulated, including:

[0084] Step S6.2.1: Construct an elastic-plastic contact model based on the total potential energy and the apparent inclination angle;

[0085] Step S6.2.2: Calculate the normal stress distribution according to the elastic-plastic contact model and determine the contact unit;

[0086] In this embodiment, the contact unit is a grid unit with an area of ​​∆x obtained by dividing the total shear distance between the upper structure surface and the lower two structures. Each micro-convex body is represented by a different number of contact units according to its size. Micro-convex body is a macroscopic concept, such as Figure 5 As shown in the figure, the real structural surface of the rock mass is uneven, and the contact problem between the upper and lower structural surfaces can be simplified to the contact problem between micro-convex bodies.

[0087] Step S6.2.3: Calculate the roughness angles of all contact elements according to the normal stress distribution, and find the maximum values ​​of all roughness angles;

[0088] Step S6.2.4: Calculate the local friction force on the contact element and the yield force of the contact element;

[0089] Step S6.2.5: Calculate the total wear area of ​​the micro-asperities when the yield force of the contact element is greater than the local friction force on the contact element;

[0090] Step S6.2.6: When the yield force of the contact unit is less than or equal to the local friction force on the contact unit, the heights of the upper structural surface and the lower structural surface are modified by using the maximum value of the roughness angle, and the modified heights of the upper structural surface and the lower structural surface are substituted into the elastic-plastic contact model, and return to step S6.2.1;

[0091] Step S6.2.7: Calculate the shear stress distribution based on the local friction force on the contact unit, and calculate the wear distribution based on the normal stress distribution to achieve numerical simulation of the direct shear test geometric numerical model after meshing.

[0092] In this embodiment, the control equation of the direct shear process of the real structural surface of the rock considering wear is established, and the control equation is input into the COMSOL Multiphysics software. The material properties are assigned to the direct shear model of the real structural surface of the rock considering wear, and boundary conditions are applied, and finally meshing is performed. The direct shear model of the rock sample considering the wear of the real structural surface of the rock is calculated, and the calculation is completed. The ultimate shear strength and residual shear strength of the direct shear process of the real structural surface of the rock mass considering geological and engineering effects are analyzed, and the stress distribution and wear distribution of the direct shear process of the real structural surface of the rock mass considering geological and engineering effects are characterized, and the destruction mechanism of the direct shear process of the real structural surface of the rock mass is more accurately revealed by combining macroscopic and microscopic.

[0093] The control equation of the direct shear process of the rock sample considering the wear of the real structural surface of the rock mass is as follows:

[0094] The total shear distance between the upper and lower structural surfaces is divided into several shear steps with a mesh size of ∆x.

[0095] For each shear step, the local friction force on contact element i can be calculated as follows:

[0096] (1);

[0097] (2);

[0098] Where A is the area of ​​the contact unit, σ ni is the local normal stress of contact element i, is the basic friction angle of rock, θ r is the local roughness angle of contact element i.

[0099] The total potential energy V of the elastic contact problem between two structural surfaces is calculated as follows:

[0100] (3);

[0101] Among them, Area represents the area of ​​the contact surface, is the normal stress, is the normal displacement of the upper and lower surfaces in the contact area Area, The total prescribed displacement of the two contacting surfaces in the contact region is based on the assumption of geometric interference. The solution calculates the surface displacement caused by the normal stress on the surface of a semi-infinite elastic body, expressed as a Green's function.

[0102] (4);

[0103] in, is the influence function of the normal deformation at the (x,y) position, which depends on Unit stress at a location.

[0104] (5);

[0105] Where v is Poisson's ratio and E is Young's modulus.

[0106] In this contact model, the normal stress that causes plastic deformation is considered as if the rock micro-asperity deformation is an ideal elastic-plastic material, and the plastic deformation is confined to a small local area. In this case, the energy dissipation caused by plastic deformation is added to the total potential energy and is recorded as:

[0107] (6);

[0108] in, is the composite incremental surface displacement in the plastic deformation zone where the contact stress reaches the rock hardness H, σ n >H; H is a parameter that describes the rock's resistance to inelastic deformation.

[0109] (7);

[0110] in, It is the incremental displacement of the two contact surfaces when the contact stress reaches the rock hardness.

[0111] The angle of local roughness is related to the shear direction and can be calculated by connecting the midpoints to the edges of the square element and the average apparent inclination of the four triangular faces of each contact element. The apparent inclination angle θ is calculated as follows:

[0112] (8);

[0113] in, is the unit normal vector, is the unit vector in the shear direction.

[0114] Wear occurs when the local friction force is greater than the surface yield strength. The Mohr-Coulomb model is used to determine the yield force f of the contact element. yi :

[0115] (9);

[0116] Among them, c and are the cohesion and friction angle of the rock respectively. If the friction force is greater than the yield force of the rock, that is , shear wear will permanently change the local surface geometry and reduce the local friction (shear resistance) to allow subsequent shear displacement.

[0117] The micro-convex geometry correction method is used to simulate the shear process, and the local friction is reduced by reducing the local roughness angle. Specifically, for any contact element, if the friction force is greater than the yield force, the target roughness angle can be determined by back calculation using the following formula.

[0118] (10);

[0119] On this basis, the target roughness angle is calculated back, see Appendix. Figure 4 , in order to make the roughness angle equal to the target angle, the height of the two front vertices of the lower surface unit (i.e., the lower structural surface) will be lowered. At the same time, the two rear vertices of the upper surface unit (i.e., the upper structural surface) will be moved up to make the roughness angle equal to the target angle. After the surface modification, the volume between the upper and lower surfaces at the contact unit is worn away. Since the surface modification affects the roughness angle and contact stress of the adjacent units, the micro-convex body geometry correction is performed through iteration until the local friction force of all contact units is less than or equal to the local yield force. Therefore, the upper surface will slide over the lower surface along the maximum roughness angle of all contact units.

[0120] The total shear force can be obtained by summing the local friction forces at each contact element:

[0121] (11);

[0122] Where j is the shear step, N c is the total number of contact elements, A t is the projected area of ​​the structural surface on the xy plane, that is , where L x and L y are the length and width of the rock respectively.

[0123] Normal displacement δ during shearing n Shear expansion d caused by sliding of the upper surface along the maximum roughness angle of all contact elements z and the crack closure caused by the normal stress u z Determine, expressed by the following formula:

[0124] (12);

[0125] Since the local shear stress is calculated according to the friction law based on the calculated local normal stress, the elastic surface deformation caused by the local shear stress is neglected in the model.

[0126] The normal force is related to the contact area and the normal stress:

[0127] (13);

[0128] Among them, F N is the normal force.

[0129] Take two mutually contacting micro-convex bodies on the upper and lower real structural surfaces, and one micro-convex body moves and contacts with the other micro-convex body, forming a junction with a diameter of D, and then moves away, see the attached Figure 5 The diameter D represents the average diameter of m contact units i, and the number of micro-convex bodies is represented by t, from which we can conclude:

[0130] (14);

[0131] (15);

[0132] Where t is the number of asperities.

[0133] The wear length of the asperity is defined as the length over which the contact is formed and broken again, which is of the same order of magnitude as the average diameter D. The total number of contact points along the path in the x direction is calculated as follows:

[0134] (16);

[0135] Where N is the total number of contact points along the path in the x direction.

[0136] Since not every formation and destruction of micro-contact will lead to the shedding of wear particles, it is assumed that the probability of wear particle formation is k, such as Figure 4 As shown, the total volume of the wear particles formed is:

[0137] (17);

[0138] Where G is the total volume of wear particles.

[0139] definition , the wear law is obtained as follows:

[0140] (18);

[0141] Among them, k abrasion is the wear factor. In addition, it is assumed that wear particles will not accumulate between the contact surfaces. Therefore, the secondary wear caused by wear particles on the structural surface in the subsequent shear process can be ignored.

[0142] Analyze the ultimate shear strength and residual shear strength of the direct shear process of the real structural surface of the rock mass considering geological and engineering effects, and characterize the stress distribution and wear distribution of the direct shear process of the real structural surface of the rock mass considering geological and engineering effects. See Appendix Figure 6 (1) and attached Figure 6 (2) Combining macroscopic and microscopic observations, the failure mechanism of the direct shear process on the real structural surface of the rock mass can be more accurately revealed.

[0143] The various embodiments in the present application are described in a progressive manner, and the same or similar parts between the various embodiments can be referenced to each other, and each embodiment focuses on the differences from other embodiments.

[0144] The protection scope of the present application is not limited to the above-mentioned embodiments. Obviously, those skilled in the art can make various changes and modifications to the present disclosure without departing from the scope and spirit of the present disclosure. If these changes and modifications fall within the scope of the claims of the present disclosure and their equivalents, the intention of the present disclosure also includes these changes and modifications.

Claims

1. A method for simulating direct shear numerical tests on real rock mass structural surfaces, characterized in that: include: Obtain standard rock samples; On the standard rock sample, artificial fractures are prepared by Brazilian splitting; The surface of the artificial fracture is scanned using 3D scanning technology to obtain point cloud data of the real structural surface of the rock mass; Establishing a direct shear test geometric numerical model of the real structural surface of the rock mass based on the point cloud data; According to the geometric numerical model of the direct shear test of the real structural surface of the rock mass, a control equation group considering the wear of the real structural surface of the rock mass is established; The control equations include: local friction force on the contact unit, total potential energy, apparent inclination angle, yield force of the contact unit, roughness angle, total shear force, normal displacement during shearing, normal force, total number of contact points, total wear area and wear law; According to the control equations, the numerical simulation of the direct shear test of the real structure surface of the rock mass considering wear is realized, including: Under the condition of considering wear, the material properties are assigned and boundary conditions are imposed in the direct shear test geometric numerical model of the real structural surface of the rock mass, and the direct shear test geometric numerical model of the real structural surface of the rock mass is meshed; According to the governing equations, the meshed direct shear test geometric numerical model is numerically simulated; According to the control equations, the direct shear test geometric numerical model after meshing is numerically simulated, including: Step S6.2.1: Construct an elastic-plastic contact model based on the total potential energy and the apparent inclination angle; Step S6.2.2: Calculate the normal stress distribution according to the elastic-plastic contact model and determine the contact unit; Step S6.2.3: Calculate the roughness angles of all contact elements according to the normal stress distribution, and find the maximum values ​​of all roughness angles; Step S6.2.4: Calculate the local friction force on the contact element and the yield force of the contact element; Step S6.2.5: Calculate the total wear area of ​​the micro-asperities when the yield force of the contact element is greater than the local friction force on the contact element; Step S6.2.6: When the yield force of the contact unit is less than or equal to the local friction force on the contact unit, the heights of the upper structural surface and the lower structural surface are modified by using the maximum value of the roughness angle, and the modified heights of the upper structural surface and the lower structural surface are substituted into the elastic-plastic contact model, and return to step S6.2.1; Step S6.2.7: Calculate the shear stress distribution according to the local friction force on the contact unit, and calculate the wear distribution according to the normal stress distribution, so as to realize the numerical simulation of the direct shear test geometric numerical model after meshing; According to the total potential energy and apparent inclination angle, an elastic-plastic contact model is constructed, and the calculation formula is as follows: Where V is the total potential energy, Area is the area of ​​the contact surface, and σ n (x, y) is the normal stress, is the normal displacement of the upper and lower surfaces in the contact area Area, is the total prescribed displacement of the two contact surfaces in the contact region based on the geometric interference assumption, Δu zp (x, y) is the composite incremental surface displacement in the plastic deformation zone where the contact stress reaches the rock hardness H, σ n >H, H is a parameter describing the rock's resistance to inelastic deformation, is the incremental displacement of the two contact surfaces until the contact stress reaches the rock hardness, is the unit normal vector, is the unit vector in the shear direction.

2. The method for simulating direct shear numerical tests of real rock mass structural surfaces according to claim 1, characterized in that: The three-dimensional scanning technology is used to scan the surface of the artificial fracture to obtain point cloud data of the real structural surface of the rock mass, including: The surface of artificial fractures is scanned using 3D scanning technology to obtain point cloud data of the real structural surface of the rock mass; Performing noise reduction processing on the point cloud data to obtain noise-reduced point cloud data; The denoised point cloud data is subjected to coordinate system transformation to obtain point cloud data of the upper structural surface and point cloud data of the lower structural surface; Place the point cloud data of the upper structural surface and the point cloud data of the lower structural surface in the same coordinate system; The point cloud data in the same coordinate system is meshed to obtain meshed point cloud data.

3. The method for simulating direct shear numerical tests of real rock mass structural surfaces according to claim 1, characterized in that: The direct shear test geometric numerical model of the real structural surface of the rock mass is established based on the point cloud data, including: A cube is used to simulate a standard rock sample; Based on the simulated standard rock specimens, the gridded point cloud data is used as a parameterized surface to generate a direct shear test geometric numerical model of the real structural surface of the rock mass.

4. The method for simulating direct shear numerical tests of real rock mass structural surfaces according to claim 1, characterized in that: According to the normal stress distribution, the roughness angle of all contact elements is calculated as follows: Among them, θ r is the target roughness angle, f y is the yield force of the contact element, A is the area of ​​the contact element, σ n is the local normal stress of the contact element, is the basic friction angle of standard rock sample.

5. The method for simulating direct shear numerical tests of real rock mass structural surfaces according to claim 1, characterized in that: The local friction force on the contact unit is calculated as follows: A=(Δx) 2 Where A is the area of ​​the contact unit, σ ni is the local normal stress of contact element i, is the basic friction angle of the standard rock sample, θ r is the local roughness angle of contact element i, f fi is the local friction force on contact element i, Δx is the shear step; The yield force of the contact unit is calculated as follows: Among them, f yi is the yield force of contact unit i, c is the cohesive force of the standard rock specimen, is the friction angle of the standard rock sample, A is the area of ​​the contact unit, σ ni is the local normal stress of contact element i; The total wear area is calculated as follows: Where G is the total wear area, σ n is the local normal stress of the contact unit, k is the probability of wear particle formation, N is the total number of contact points along the path x, D is the average diameter of m contact units i, F N is the normal force.

6. The method for simulating direct shear numerical tests of real rock mass structural surfaces according to claim 1, characterized in that: The shear stress distribution is calculated based on the local friction force on the contact unit, and the wear distribution is calculated based on the normal stress distribution. The calculation formula is as follows: Among them, a i is the shear stress of contact element i, G i is the wear of contact unit i, f fi is the local friction force on contact element i, A t is the projection area of ​​the structural surface on the xy plane, that is, A t =L x ×L y , where L x is the length of the standard rock sample, L y is the standard rock sample width, F N is the normal force, σ ni is the local normal stress of contact element i, and x is the path.

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