A graphical calculation method for rock mass simulation analysis

Abstract

The present invention discloses a graphic calculation method for rock mass simulation analysis, which relates to the technical field of rock mass simulation analysis. This graphic calculation method uses the three-dimensional graphics in CAD software as the main medium, and uses the cutting command to divide the three-dimensional graphics into three-dimensional graphics of various forms to simulate the fault, fracture, and joint structural characteristics of the rock mass, thereby completing the geometric modeling of the rock mass. The development of the physical engine represented by computer graphics in the present invention has greatly overcome the existing problems. The rigid body simulation and rigid body animation in the physical engine can not only simulate the movement, collision, and cracking problems between graphics, but also for large-capacity graphic calculations, special graphic calculation hardware can even be used. Graphic calculation can not only handle dynamic problems, but also provides great convenience for solving the continuous-discontinuous medium problems unique to geotechnical engineering and even the mixed element calculation problems.

Description

Technical Field

[0001] The present invention relates to the technical field of rock mass simulation analysis, and specifically to a graphic calculation method for rock mass simulation analysis. Background Art

[0002] At present, the numerical analysis methods for geotechnical engineering mainly include calculation methods such as the finite element method (FEM), discrete element method (DEM), discontinuous deformation analysis (DDA), and numerical manifold method (NMM). These methods usually do not provide modeling functions, but import the model after modeling with CAD software, and then perform analysis and post-processing processes. In numerical analysis, especially in the discontinuous numerical methods of rock and soil, block search and collision calculation are usually the key to numerical analysis, which are generally solved by mathematical methods. Problems such as slow speed and difficult solution have always been the drawbacks in this field. In addition, most of these methods are based on differential equations, and it is not easy for the calculation results to converge for discontinuous problems, occupying a large amount of computing resources.

[0003] Based on this, a graphic calculation method for rock mass simulation analysis is now provided, which can eliminate the drawbacks existing in the existing methods. Summary of the Invention

[0004] The purpose of the present invention is to provide a graphic calculation method for rock mass simulation analysis to solve the problems in the background art.

[0005] To achieve the above purpose, the present invention provides the following technical solutions:

[0006] A graphic calculation method for rock mass simulation analysis includes the following steps:

[0007] Step 1: Taking the 3D graphics in CAD software as the main medium, using the slice command to divide the 3D graphics into 3D graphics of various forms to simulate the fault, fracture, and joint structure characteristics of the rock mass, and completing the geometric modeling of the rock mass;

[0008] Step 2: Using the slice command to divide along the grid layout, dividing the rock mass area into 3D graphic units of various forms, performing graphic calculations using the boundary representation (Brep) of the 3D graphics, extracting units of different forms using the secondary development program, and directly using them as the numerical grids for finite element analysis after processing; for the discrete element method and discontinuous deformation analysis, for the geometric model of the rock mass, using the Monte Carlo or random medium method for each rock mass area, randomly dividing the blocks into various blocks, performing graphic calculations using the boundary representation of the 3D graphics, and obtaining the block boundary data using the secondary development program;

[0009] Step 3: Use the 3D graphics in CAD to calculate the physical parameters of the block volume, weight, center of mass, rotational inertia, and the distance relationship between blocks, determine the contact chain, contact relationship, and contact parameters of the block unit, and export the above data and block boundary expression data together using the secondary development data export interface;

[0010] Step 4: Use the data import interface developed in Python to import the geometric and physical parameters exported in step 3 into the software (blender) with physical engine function, and use the physical engine of the software to implement block motion analysis;

[0011] Step 5: Based on the frame step size and motion trajectory of the physical engine in step 4 and the contact chain fracture results, inversely analyze the movement speed and acceleration of the rock block and the transition process from continuous to discontinuous;

[0012] Step 6: Combining the above motion with near-field dynamics can be applied to geotechnical engineering and coal mining projects such as rock cracking, landslides, tunnel excavation, and coal mine collapse.

[0013] On the basis of the above technical solution, the present invention also provides the following optional technical solution:

[0014] In an optional solution: the regular grid division system (rectangular coordinate system) is constructed, and the three dimensions of xyz are divided regularly with equal lengths. According to the finite element grid criterion, the shapes below the hexahedron in the unit can be used directly, and the shapes above the hexahedron need secondary division.

[0015] In one alternative: the peridynamic formula:

[0016]

[0017] ρ(x) represents the density of material point x at time t; represents the acceleration of the material point x at time t; u(x, t) and u(x', t) represent the displacements of the material points x and x'; b(x, t) represents the external force on the material point x; the function f is the interaction force function between the material points x and x', which is only related to the deformation of the bond between the material points x and x'; H is the scope of the position point.

[0018] For rock mass, the external force is mainly gravity, then

[0019] b(x,t)=ρ(x)g (2)

[0020] g is the gravitational constant, 9.8m / s 2 ;

[0021] There are two sources of function f. One is the normal force F. n, mainly reflected in the crack resistance and directional movement of the rock mass, and its index is the normal stress of the rock mass; one is the shear stress F s , mainly reflected in the frictional force and cohesion of the rock mass;

[0022] Normal force: F n =∫ S f n dS≤σS (3)

[0023] Tangential force: F s =∫ S f s dS+∫ S f t dS≤μF n +cA (4)

[0024] σ is the tensile strength, μ is the friction coefficient of the contact surface, F n is the contact force between two surfaces, c is the cohesion, and A is the contact area;

[0025] For the normal force F n , when cracks appear in the rock mass, the acting force disappears. Multiply both sides of formula (3) by the time step, and (3) becomes:

[0026] F n Δt = ∫ S f n ΔtdS = ∫ S I n dS = k∑I n ≤σSΔt (5)

[0027] I n is the impulse received by the particle, Δt is the time step, and k is the relationship coefficient. The cracking of the rock mass can be controlled by the impulse received by the rock mass;

[0028] For the tangential force F s , after the rock cracks, the cohesion of the rock mass drops significantly and can be ignored. Only the frictional force between the rock masses is considered during the movement of the rock mass;

[0029] Method for controlling and setting cracking parameters: Set rigid body spring constraints in the rigid body;

[0030] Normal spring constraint threshold: σAΔt; A is the contact area of the rock mass block, and Δt is the time step;

[0031] Tangential spring constraint threshold: cA; A is the contact area of the rock mass block;

[0032] Friction coefficient between surfaces: μ.

[0033] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0034] The development of physical engines represented by computer graphics in the present invention has greatly overcome the above problems. Rigid body simulation and rigid body animation in physical engines can not only simulate the movement, collision, and fragmentation problems between graphics, but also use specialized graphics computing hardware for large-capacity graphics calculations. Graphics computing can not only handle dynamic problems, but also provides great convenience for solving the continuous-discontinuous medium problems unique to geotechnical engineering and even the mixed element calculation problems. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic structural diagram of the present invention according to the mesh dissection system.

[0036] Figure 2 It is a schematic structural diagram of the present invention according to the finite element mesh criterion.

[0037] Figure 3 It is a schematic diagram of the present invention using graphics BREP for calculation.

[0038] Figure 4 It is a schematic diagram of random medium filling in the present invention.

[0039] Figure 5 It is a schematic diagram of Monte Carlo random dissection in the present invention.

[0040] Figure 6 It is a schematic diagram of the calculation in Calculation Example 1 of the present invention.

[0041] Figure 7 It is a graph of the graphics calculation result in Calculation Example 1 of the present invention.

[0042] Figure 8 It is a schematic structural diagram of the separation phenomenon in the coal mining subsidence analysis in Calculation Example 2 of the present invention.

[0043] Figure 9 It is a schematic structural diagram of the key layer phenomenon in the coal mining subsidence analysis in Calculation Example 2 of the present invention.

[0044] Figure 10 It is a schematic diagram of the rock friction and cohesion in the present invention.

[0045] Figure 11 It is a flowchart of the rock mass geometric modeling in the present invention.

[0046] Figure 12 It is a flowchart of the finite element analysis in the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0047] In order to make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0048] In one embodiment, asFigures 1 - 12 As shown in the figure, a graphic calculation method for rock mass simulation analysis includes the following steps:

[0049] 1. Taking the three-dimensional graphics in CAD software as the main medium, using the cutting command (slice) to divide the three-dimensional graphics into three-dimensional graphics of various forms to simulate the structural characteristics such as faults, fissures, and joints of the rock mass, and completing the geometric modeling of the rock mass;

[0050] 2. On this basis, (1) for finite element analysis, construct a regular grid system for the rock mass area, use the cutting command to divide along the grid layout, divide the rock mass area into three-dimensional graphic units of various forms, use the boundary representation (Brep) of the three-dimensional graphics for graphic calculation, and use the secondary development program to extract units of different forms, and directly use them as the numerical grids for finite element analysis after processing; (2) for discrete element and discontinuous deformation analysis, for the geometric model of the rock mass, use the Monte Carlo or random medium method for each rock mass area, randomly divide the blocks into various blocks, use the boundary representation of the three-dimensional graphics for graphic calculation, and use the secondary development program to obtain the block boundary data;

[0051] 3. Use the three-dimensional graphics in CAD to calculate physical parameters such as the volume, weight, centroid, and moment of inertia of the blocks, as well as the distance relationship between the blocks, determine the contact chain, contact relationship, and contact parameters of the block units, and export the above data and the block boundary representation data together using the secondary development data export interface;

[0052] 4. Use the data import interface developed by Python to import the geometric and physical parameters exported in step 3 into the software (blender) with the function of a physical engine, and use the physical engine of the software to realize the block motion analysis;

[0053] 5. According to the frame step size, motion trajectory, and contact chain fracture results of the physical engine in 4, inversely analyze the motion speed and acceleration of the rock blocks and the process of the rock mass transitioning from continuous to discontinuous;

[0054] 6. Combining the above motion and peridynamics can be applied to geotechnical engineering and coal mining engineering such as rock mass cracking, landslides, tunnel excavation, and coal mine collapses, with a simple implementation process and a very broad application prospect.

[0055] In this application, the graphic calculation of the mesh generation for the finite element method; 1) Define the rock mass area, use the cutting command (slice) to divide the three-dimensional graphics into three-dimensional graphics of various forms to simulate the structural characteristics such as faults, fissures, and joints of the rock mass, Figure 1 ; 2) Construct a regular mesh generation system (rectangular coordinate system), and perform regular meshing with equal lengths in the three directions of x, y, and z, Figure 2; 3) According to the finite element mesh criterion, the shapes below the hexahedron in the element can be directly used, and those above the hexahedron need to be re-meshed. Figure 3 ; 4) Using the graphic BREP for calculation, it can be directly converted into the format required by the finite element, and the process is as shown in the figure.

[0056] Discretization of rock mass for discrete element and discontinuous analysis: 1) Define the rock mass area, and use the cutting command (slice) to divide the 3D graphics into various 3D graphics of different shapes to simulate the structural features such as faults, fractures, and joints of the rock mass. Figure 1 ; 2) Random medium filling: Extract the boundaries of each area of the rock mass, import them into Blender, use Blender to emit particles with random diameters, enable the gravity effect, and fill each area to form a random medium area. Figure 4 ; 3) Monte Carlo random cutting: Extract the solids of each area of the rock mass, randomly set the joint structural features, and perform random cutting to form a random rock mass discretization.

[0057] Data interface between CAD and Blender:

[0058] SOLID

[0059] C,x0,y0,z0 * Center coordinates of the solid (x0,y0,z0)

[0060] V,x1,y1,z1 * Corner point coordinates (x1,y1,z1)

[0061] V,x2,y2,z2

[0062] E,1,2 * The edge is composed of two corner points (V1,V2), and the order of the starting point and the ending point represents the direction of the edge

[0063] E,2,3

[0064] F,1,2,3,4 * The face is composed of more than three corner points (V1,V2,V3,V4), and the rotation direction of the point connection and the normal direction of the face conform to the right-hand screw rule

[0065] F,1,2,5,4

[0066] #SOLID*# Indicates the end of the solid geometry data

[0067] LINK

[0068] L,1,2,F,1,2,P,p1,p2,p3 * There is an association between face 1 of solid 1 and face 2 of solid 2, and the association parameters are three-dimensional p1,p2,p3

[0069] L,1,2,E,1,3,P,p1,p2,p3 *There is an association between edge 1 of entity 1 and edge 3 of entity 2, and the association parameters are p1, p2, p3 (two-dimensional)

[0070] #LINK*# Indicates the end of the geometric data of this entity

[0071] PROPERTY

[0072] P,1,volumn,mass,density,Ix,Iy,Iz,color…… *Among the properties of entity 1, the volume is volumn, the mass is mass, the density is desity, the moments of inertia are lx, Iy, Iz, and the color is color……

[0073] #PROPERY

[0074] The data interface includes three parts. SOLID represents the three-dimensional entity part, LINK represents the association between three-dimensional entities, and PROPERTY represents various properties of three-dimensional entities.

[0075] The keywords C represents the center point, V represents the corner point, E represents the edge, F represents the face, L represents the association, P represents the property, and # represents the end;

[0076] Method for determining the transition from continuous to discontinuous fracture of rock mass using the peridynamic method:

[0077] 1) Peridynamic formula

[0078]

[0079] ρ(x) represents the density of the material point x at time t; represents the acceleration of the particle x at time t; u(x,t) and u(x',t) represent the displacements of the material points x and x'; b(x,t) represents the external force acting on the material point x; the function f is the interaction force function between the material points x and x', which is only related to the deformation of the bond between the material points pair x and x'; H is the influence domain of the position point.

[0080] For rock mass, the external force is mainly gravity, then

[0081] b(x,t) = ρ(x)g (2)

[0082] g is the gravitational constant, 9.8 m / s 2 ;

[0083] The function f has two sources. One is the normal force F n , which mainly reflects the crack resistance and directional movement of the rock mass, and its index is the normal stress of the rock mass; the other is the shear stress F s , which mainly reflects the frictional force and cohesion of the rock mass.

[0084] Normal force: F n = ∫ S f n dS ≤ σS (3)

[0085] Tangential force: F s = ∫ S f s dS + ∫ S f t dS ≤ μF n + cA (4)

[0086] σ is the tensile strength, μ is the friction coefficient of the contact surface, F n is the contact force between two surfaces, c is the cohesive force, A is the contact area;

[0087] For the normal force F n When cracks appear in the rock mass, the acting force disappears. Multiply both sides of formula (3) by the time step, and (3) becomes:

[0088] F n Δt = ∫ S f n ΔtdS = ∫ S I n dS = k∑I n ≤ σSΔt (5)

[0089] I n is the impulse received by the particle, Δt is the time step, and k is the relationship coefficient. The cracking of the rock mass can be controlled by the impulse received by the rock mass.

[0090] For the tangential force F s After the rock cracks, the cohesive force of the rock mass drops significantly and can be ignored. Only the friction force between the rock masses is considered during the movement of the rock mass.

[0091] 2) Method for controlling and setting cracking parameters: Set rigid body spring constraints in the rigid body.

[0092] Normal spring constraint threshold: σAΔt; A is the contact surface area of the rock mass block, Δt is the time step;

[0093] Tangential spring constraint threshold: cA; A is the contact surface area of the rock mass block;

[0094] Friction coefficient between surfaces: μ;

[0095] Example 1: A typical GOODMAN-BRAY example (source: Goodman, R.E. and Bray, J.W. (1976) Toppling of Rock Slopes. Proceedings of the Specialty Conference on Rock Engineering for Foundations and Slopes, 2, 201-234.). Based on the original calculation, there are adjustments. The schematic diagrams are as shown in Figure 6 and Figure 7 as follows. The friction coefficient μ = 0.785 and the density is 25 KN / m3. The calculation results show that blocks 1-2 slide, blocks 3-14 topple, and blocks 15-16 remain stationary. Considering the differences from the original example model, the calculation results are correct;

[0096] Example 2: Coal mining subsidence analysis. In a certain coal mine, the mining face height is 8 m, the overlying rock thickness is 20 m, the unit weight is 26.7 KN / m3, the friction angle is 28°, the tensile strength σ is 4 Mpa, the cohesion c is 1.2 Mpa, and the mining depth is 100 m. The calculation results are as shown in the figure, and the separation phenomenon and key stratum phenomenon can be observed intuitively, which is consistent with the relevant literature.

[0097] As described above, it is only the specific implementation manner of the present disclosure, but the protection scope of the present disclosure is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present disclosure can easily think of changes or substitutions, which should be covered within the protection scope of the present disclosure. Therefore, the protection scope of the present disclosure shall be subject to the protection scope of the claims.

Claims

1. A graphic calculation method for rock mass simulation analysis, characterized in that, It includes the following steps: Step 1: Taking the 3D graphics in CAD software as the main medium, using the slice command in the CAD software to divide the 3D graphics into 3D graphics of various forms to simulate the fault, fracture, and joint structure characteristics of the rock mass, and completing the geometric modeling of the rock mass; Step 2: Using the slice command to perform division along the grid layout, dividing the rock mass area into 3D graphic units of various forms, using the boundary representation (Brep) of the 3D graphics for graphic calculation, and using the secondary development program to extract units of different forms, which are directly used as the numerical grid for finite element analysis after processing; for discrete element and discontinuous deformation analysis, for the geometric model of the rock mass, using the Monte Carlo or random medium method for each rock mass area, randomly dividing the blocks into various blocks, using the boundary representation of the 3D graphics for graphic calculation, and using the secondary development program to obtain the block boundary data; Step 3: Using the 3D graphics in CAD to calculate physical parameters such as the volume, weight, centroid, and moment of inertia of the blocks, as well as the distance relationship between the blocks, determining the contact chain, contact relationship, and contact parameters of the block units, and exporting the above data and the block boundary representation data together using the secondary development data export interface; Step 4: Using the data import interface developed by Python to import the geometric and physical parameters exported in Step 3 into the software blender with physical engine functions, and using the physical engine of the software to implement the block motion analysis; Step 5: According to the frame step size, motion trajectory, and contact chain fracture results of the physical engine in Step 4, inversely analyze the motion speed and acceleration of the rock blocks and the process of the rock mass transitioning from continuous to discontinuous; Peridynamics formula （1） denote the density of the material point at a moment ; denote the acceleration of the particle at a moment ; and denote the displacement of the material point and ; denote the external force received by the material point ; The function is the interaction force function between the material point and , which is only related to the deformation of the bond between the material point pair and ; is the scope of the position point; For the rock mass, if the external force is gravity, then （2） is the gravitational constant, 9.8 m / s 2 ; Function There are two sources. One is the normal force , which is reflected in the crack resistance and directional movement of the rock mass, and its index is the normal stress of the rock mass; the other is the shear stress , which is reflected in the frictional force and cohesion of the rock mass; Normal force: (3) Tangential force: (4) is the tensile strength, is the contact surface friction coefficient, is the contact force between two surfaces, is the cohesion force, is the contact area; Step 6: Combining the above motion and peridynamics and applying them to geotechnical engineering and coal mining engineering such as rock mass cracking, landslides, tunnel excavation, and coal mine collapse.

2. The graphical calculation method for rock mass simulation analysis according to claim 1, characterized in that Construct a regular grid meshing system, with equal-length regular meshing in the three directions of x, y, and z. According to the finite element grid criterion, the shapes below the hexahedron in the unit can be directly used, and those above the hexahedron need secondary meshing.

3. The graphic calculation method for rock mass simulation analysis according to claim 1, wherein: For the normal force When cracks appear in the rock mass, the acting force disappears. Multiply both sides of formula (3) by the time step, and (3) becomes: （5） is the impulse received by the particle, is the time step, is the relationship coefficient, and the rock mass cracking is controlled by the impulse received by the rock mass; For the tangential force After the rock cracks, the cohesion of the rock mass drops significantly and can be ignored. Only the frictional force between the rock masses is considered during the movement of the rock mass; Cracking parameter control setting method: setting rigid body spring constraints in the rigid body; Normal spring constraint threshold: ; is the contact area of the rock mass block, is the time step; Tangential spring constraint threshold: ; is the contact area of the rock mass block Coefficient of friction between surfaces: .

Images