3DEC数值模拟方法课件

1、3DEC数值模拟方法,2013 依泰斯卡 (,1,PPT学习交流,提 纲 3DEC(5.0)软件特点 3DEC(5.0)理论基础 3DEC(5.0)新功能 3DEC (5.0)算例分析,2,PPT学习交流,提 纲 3DEC(5.0)软件特点 3DEC(5.0)理论基础 3DEC(5.0)新功能 3DEC (5.0)算例分析,3,PPT学习交流,What is 3DEC?,A Distinct Element code that allows the simulation of the interaction of blocks e.g. jointed rock mass, masonry w

2、all,4,PPT学习交流,What is 3DEC?,Discontinuities are regarded as distinct boundary interactions between blocks Contacts are automatically updated as calculation progresses large displacements are allowed Non-linear force displacement behavior may be assigned to contacts (joints),5,PPT学习交流,What is 3DEC?,3

3、DEC blocks are rigid or deformable,Deformable blocks are automatically meshed with tetrahedra to simulate a non-linear continuum,6,PPT学习交流,What is 3DEC?,Solves the full dynamic equations of motion even for quasi-static problems Allows for large displacements, rotations and dynamic analyses,7,PPT学习交流

4、,What is 3DEC?,3DEC is best suited to modeling discontinuous materials (containing many intersecting discontinuities in 3D),that exhibit nonlinear behavior,8,PPT学习交流,矿层分布模型,地质构造分布,开挖后对地表建筑物的影响,屈服矿柱分布情况,矿山开采稳定性分析研究,当前开采条件下矿柱几乎没有屈服 断层影响不大,9,PPT学习交流,矿藏分布三维模型,拉底步骤,矿岩三维节理模型,拉底后矿岩出露模型,矿岩崩落数值模拟,对崩落速度和 规模进行

5、预测,10,PPT学习交流,崩落过程模拟,11,PPT学习交流,Nuclear Waste Disposal,Shotcrete,Concrete,Canister cover,Localization in claystone at 6 months,Claystone,Reproduced with permission of ANDRA,12,PPT学习交流,Hydraulic Fracture,Discrete Fracture Network,Fractured reservoir model,13,PPT学习交流,Hydraulic Fracture,Fluid pressure

6、in joints during injection Top portion of reservoir hidden for ease of viewing,14,PPT学习交流,Microseismicity,Fractured rock volume loaded axially with 10 MPa confining stress,100 m,15,PPT学习交流,Fundamental Rock Mechanics,Simulated unconfined compression test on crystalline rock sample,Displacements,Grain

7、 structure,Exaggerated deformation,16,PPT学习交流,Slope Stability,Automatic Factor of Safety calculation for 3D slopes Uses Shear Strength Reduction method,Abutment stability assessment at Hongrich arch dam1,1Koliji et al, 2001. Int. J. Hydropower including complete detachment recognizes new interaction

8、s (contact) automatically as the calculation progresses A discrete element code will embody an efficient algorithm for detecting and classifying contacts. It will maintain a data structure and memory allocation scheme that can handle many hundreds or thousands of discontinuities or contacts.,The nam

9、e “Distinct Element Method” is used for a DEM that uses an explicit dynamic solution to Newtons laws of motion.,*Cundall,P.A., and R.D. Hart.”Numerical Modeling of Discontinua,” Engineering Computations, 9(2), 101-113 (1992),24,PPT学习交流,Finite element codes for modeling “discontinua” are often modifi

10、ed continuum programs, which cannot handle general interaction geometry (e.g. many intersecting joints). Their efficiency may degenerate drastically when connections are broken repeatedly.,25,PPT学习交流,Distinct Element Method,Three aspects . Geometry Contact mechanics Solid body mechanics,26,PPT学习交流,D

11、istinct Element Method,Geometry Specification of shapes in 2 and 3 dimensions Interaction of pairs of contacting blocks or particles Identification of contact character between 2 blocks,27,PPT学习交流,Distinct Element Method,Specification of shapes in 2 and 3 dimensions 2 and ki is the measure of stiffn

12、ess of the elements surrounding the node. For calculations of the inter-block relative displacement, the limiting timestep is where Mmin is the mass of the smallest block in the system; and Kmin is the maximum contact stiffness. The controlling timestep is,52,PPT学习交流,53/160,MECHANICAL DAMPING,Mechan

13、ical damping is used in UDEC for static (non-inertial) solutions and for dynamic solutions. For static analysis, the approach is similar to “dynamic relaxation.” The equations of motion are damped to reach a force equilibrium state as quickly as possible under the applied initial and boundary condit

14、ions.,53,PPT学习交流,54/160,DYNAMIC RELAXATION,In dynamic relaxation blocks (and gridpoints) are moved according to Newtons law of motion. The equations of motion are damped to reach a force equilibrium state as quickly as possible Damping is velocity-proportional i.e., the magnitude of the damping forc

15、e is proportional to the velocity of the blocks. Velocity-proportional damping introduces body forces that can affect the solution. UDEC provides two different types of damping to minimize this problem for static analysis: adaptive global damping (DAMP auto) local damping (DAMP local),54,PPT学习交流,55/

16、160,ADAPTIVE GLOBAL DAMPING,Adaptive global damping is a servo-mechanism used to adjust the damping constant automatically such that the power absorbed by damping is proportional to the rate of change of kinetic energy in the system. Adjustment of the viscosity constant is made by a numerical servo-

17、mechanism that seeks to keep the ratio, R, equal to a given ratio (e.g., 0.5).,55,PPT学习交流,Damping forces are introduced to the equations of motion: where Fi is the unbalanced force,56/160,LOCAL DAMPING,The damping force, Fd is:,In UDEC the unbalanced force ratio (ratio of unbalanced force, Fi , to t

18、he applied force magnitude, Fm) is monitored to determine the static state. By default, when Fi / Fm 10-5 in UDEC then the model is considered to be in an equilibrium state.,The damping force at a gridpoint is proportional to the magnitude of the unbalanced force with the sign set to ensure that vib

19、rational modes are damped.,56,PPT学习交流,57/160,BASIS OF STATIC SOLUTIONS IN UDEC,The unbalanced force ratio (ratio of unbalanced force, Fi , to the applied force magnitude, Fm) is monitored to determine the static state. Both the adaptive global damping and local damping dynamic solution methods provi

20、de a static solution (with the effect of inertial forces minimized) provided the unbalanced force ratio reaches a small value. This is comparable to the “level of residual error” or “convergence criterion” defined for matrix solution methods used in many finite element programs. In UDEC, the level o

21、f error is quantified by the unbalanced force ratio. In both UDEC and FE solutions, the static solution process terminates when the error is below a desired value.,57,PPT学习交流,58/160,Comparison of adaptive global damping and local damping,A simple example: ten blocks slide on a rough base*,Velocity p

22、roportional to out-of-balance force with proportionality constant Dynamic relaxation with standard velocity-proportional damping Adaptive global damping Local damping,*,58,PPT学习交流,59/160,MASS (DENSITY) SCALING,For static analysis, material inertial masses can be scaled so that local critical timeste

23、ps are increased. The value of inertial mass is irrelevant to modeling static systems, provided gravity forces are correctly preserved. (Note that gravitational masses are not affected.) Critical timestep can be increased because it is proportional to . The procedure, called “density scaling,” scale

24、s the inertial density of blocks or zones based on their average block, or zone, mass. Density scaling is invoked with the MSCALE command. It is turned on automatically whenever local damping or adaptive global damping is used.,59,PPT学习交流,提 纲 3DEC(5.0)软件特点 3DEC(5.0)理论基础 3DEC(5.0)新功能 3DEC (5.0)算例分析,6

25、0,PPT学习交流,Full Features of 3DEC,1、Discontinuous medium modeled as an assemblage of convex polyhedra or concave polyhedra (formed by joining together convex polyhedra); blocks may be rigid or deformable 2、Discontinuities treated as boundary conditions between blocks 3、Motion along discontinuities gov

26、erned by linear and non-linear force-displacement relations for movements in both the normal and shear direction 4、Material models include: elastic, anisotropic, Mohr-Coulomb, Drucker Prager, bilinear plasticity, strain softening, creep, and user-defined 5、Modeling attributes may include absorbing b

27、oundaries and wave input for fully dynamic response; null blocks for excavation and backfill simulation; structural elements with general coupling to blocks,61,PPT学习交流,6、Extensive, fast interactive menu-based 3D OpenGL on-screen graphics. Available plots include: joint structure; block structure; di

28、splacement and velocity vectors and contours; joint plane displacements and stresses; structural element displacements and stresses; and, fluid flow apertures and velocities. Hard copy graphics are available in several industry standard formats 7、Utilities include a preprocessor that reads AutoCAD f

29、iles and outputs3DECdata files for polyhedra generation; tunnel generator and statistically-based joint-set generator 8、Built-in programming language (FISH) provides powerful flexibility to customize analyses 9、Explicit time marching solution that provides realistic path-dependent post peak failure

30、behavior in joints and plastic zones,Full Features of 3DEC,62,PPT学习交流,10、Modeling infinite domain problems using inner/outer region coupling and automatic radially-graded mesh generation 11、Effective stress calculation performed using pore-pressure gradients 12、Joint fluid flow with thermal and mech

31、anical coupling 13、Structural elements with cables, beams, and liners 14、Single precision, double precision, and 64bit versions are supplied 15、Automatic mesh generation in fully deformable blocks 16、Automatic time step calculation,Full Features of 3DEC,63,PPT学习交流,1、Improved performance a. Multi-thr

32、eaded stress and contact calculations, 2-3 times faster on an Intel 4-core processor b. Improved compiler optimizations c. Unjoin/Delete has been sped up by a factor of 100. d. Faster joined grid point logic 2、Improved Project support in the user interface a、Pack/Unpack Bundle of all files associate

33、d with a project b、Can be saved for archive, or sent for support c、Built in text editor performs better on large files d、Context Sensative help for commands (F1) in text editor,New or Improved Features in 3DEC 5.0,64,PPT学习交流,3、Command-line UNDO a. Undo any number of commands given interactively sinc

34、e last save point b. Implemented by playing back a record kept of all input c. All files affecting the model state kept as part of the record d. Model State pane in GUI shows record, allows copy/paste 4、Improvements to Euler equations of motion to include second order terms for fast rotation of rigi

35、d blocks 5、New WALL block type. Calculations for wall motion and wall to wall contacts are skipped to speed up model runs 6、Additional control keywords for Solve FOS,New or Improved Features in 3DEC 5.0,65,PPT学习交流,7、FISH Improvements a. Command-line debugging b. Improved error messages c. Dynamic ar

36、rays d. Zone field data functions e. C+FISHintrinsic plug-ins f. Unlimited (subject to memory limitations)FISHextra variables for blocks, zones, gridpoints, contacts and subcontacts g. InlineFISH- execute one lineFISHprograms as a parameter in a command h. Can create local variables during the LOOP

37、command,New or Improved Features in 3DEC 5.0,66,PPT学习交流,7、FISH Improvements i. EXIT LOOP to break out of a loop j. CONTINUE to skip the remaining code in a loop k. ELSE IF l. Command processor parses nested functions or arrays with arguments correctly m. Command processor can be used to assign vecto

38、r values f. FISH now supports append g. FISHarrays will reference count, and delete themselves if no internal or external symbols reference them,New or Improved Features in 3DEC 5.0,67,PPT学习交流,8、New geometry logic a. Specify geometric data separate from the model b. Can be used with Ranges, Plotting

39、 and has fullFISHaccess c. Import/Export 3D surfaces in DXF or STL formats (and two Itasca defined formats) d. Create, modify and manipulate geometric surfaces withFISH e. Paint model data onto geometric surfaces, for contouring f. Built in ability to assign groups based on counting projection inter

40、sections, similar to Space Ranger. Available for blocks, zones, gridpoints, contacts and sub-contacts g. Multiple extra variables and groups can be assigned to geometry nodes, edges, and polygons.,New or Improved Features in 3DEC 5.0,68,PPT学习交流,9、Plotting Improvements a. Zone plotting capability i.

41、Zone groups ii. Isosurfaces of zone or gridpoint data,New or Improved Features in 3DEC 5.0,69,PPT学习交流,9、Plotting Improvements b. Detachable（可分开） panes in the user interface c. Plot joint properties d. Improved mouse controls for view manipulation e. Right mouse for all camera modification, left to i

42、nteract with plot/model f. Lighting g. New Plot Export options i. Postscript ii. VRML, which can be imported into Acrobat3D iii. SVG (Scalable Vector Graphic) iv. DXF,New or Improved Features in 3DEC 5.0,70,PPT学习交流,h. New Contour Ramps（斜面） added as options to Contour plots i. Retooled User Defined D

43、ata i. Multiple extra variables and groups can be assigned to each ii. Multiple Import/Export formats j. Additional scalars added to list of values plotted from stress, strain tensors k. Improved quality of printed output i. Legends, charts, etc. are drawn at printer native resolution ii. Reduced ch

44、ance of differences between what is on the screen and what is on the page,New or Improved Features in 3DEC 5.0,71,PPT学习交流,l. Equal angle Stereonet（立体图） of principal stress/strain orientations, joints, andFISHextra variables m. Painting of calculated results on imported geometric surfaces,New or Impr

45、oved Features in 3DEC 5.0,72,PPT学习交流,10、Discrete Fracture Network support a. Generation, Import, Export, Plotting, etc b. Blocks can be cut using DFN geometry c. Different joint properties can be applied on the joint planes outside of the initial fracture extents to enable fracture propagation,New o

46、r Improved Features in 3DEC 5.0,73,PPT学习交流,11、DENSIFY command a. Uses externally defined surfaces to define3DECblock geometry b. Subdivide a range of blocks into smaller blocks c. Octree blocking capability,New or Improved Features in 3DEC 5.0,74,PPT学习交流,12、Water table definition from geometry (e.g.

47、 imported dxf) 13、INSITU command can specify principal stresses 14、Full Unicode support 15、Warning dialog box a. Warnings are accumulated in a pop-up box that does not stop command processing b. A warning level tolerance to cause the dialog to appear can be defined 16、Improved CALL command a. Can st

48、art at a given line, or at a label in the file b. Can start multiple files in one command Example: call first.dat line 30 call second.dat label lable1,New or Improved Features in 3DEC 5.0,第一个文件名,从第30行开始执行,第二个文件名,从标签lable处开始执行,注：指定标签时，“:label”必须放在行首,75,PPT学习交流,17、DENSIFY command 18、Copy to Clipboard

49、option added to the object query Information Box,New or Improved Features in 3DEC 5.0,76,PPT学习交流,18、Data in Excel Spreadsheet 19、Environment variable expansion inside strings 20、GUI command allows saving project batch processing 21、Built-in text editor performs better on large files 22、Program optio

50、nal features may now be leased 23、Security key updates can now be done directly in3DEC 24、Improved SYSTEM command a. Can pass multiple tokens, and can specify a timeout duration 25、Group logic available for blocks, zones, gridpoints, contacts and subcontacts a. Unlimited number of group slots b. Gro

51、up range elements,New or Improved Features in 3DEC 5.0,77,PPT学习交流,提 纲 3DEC(5.0)软件特点 3DEC(5.0)理论基础 3DEC(5.0)新功能 3DEC (5.0)算例分析,78,PPT学习交流,3DEC 5.0Graphics Capabilities,79,PPT学习交流,3DEC Main Window,Saved states,Console,Element infomation,Data files,Plot views,Plot item list,Caption,Legend,View infomati

52、on,Attributes,View control,Lables,80,PPT学习交流,3DEC Main Window,Edit menu,81,PPT学习交流,3DEC Main Window,Tools menu,82,PPT学习交流,3DEC Main Window,Layout menu,Panes menu,Documents menu,Help menu,83,PPT学习交流,3DEC Main Window,Layout menu,Panes menu,Documents menu,Help menu,84,PPT学习交流,3DEC Main Window,执行,新视图,复制

53、视图,输出视图,操纵模式,查询模式,item,view,information,85,PPT学习交流,Terminologies in 3DEC,86,PPT学习交流,Terms describing the attitude of an inclined plane,87,PPT学习交流,88,PPT学习交流,3DEC Files,Project File (*.3dprj) The project information related to a specific 3DEC project. This includes links to the data save to the proje

54、ct, the plot views generated for the project and the gui layout. Data File (*.3ddat) ASCII 3DEC commands that represent the problem being analyzed Save File (*.3dsav) Binary values of all state variables and user-defined conditions at stage that saved Log File (*.log) ASCII file that records text appearing on the screen into a log file