一、概述

3DEC 是一個三維數值模擬軟體，用於土壤、岩石、地下水、結構支撐和磚石以進行更精進的工程分析。 3DEC 模擬不連續介質（如節理岩石或磚石）在靜態或動態載荷下的行為。其中所使用的數值公式乃基於不連續模型的離散元素法 (DEM)。 而UDEC 則是二維版本。


不連續材料以離散塊體的組合來表現。不連續面被視為塊體與塊體之間的邊界條件；允許沿著塊體的不連續面產生大位移和旋轉。單個塊體的行為（遵循組合律和節理模型）可以是剛性或可變形的（亦即劃分為有限差分區域）材料。連續和間斷的節理型式可以在統計基礎上生成。節理構造可以直接從地質圖建構到分析模型中。 3DEC 還包含 Itasca 強大的內置腳本語言 FISH。使用 FISH，您可以添加自定義的分析功能，編寫自己的分析腳本。

Options

Options in 3DEC are sold separately from the general license, allowing users to select the program’s capabilities as meets their own analysis needs without having to purchase all features. Beginning with 3DEC Version 7, the Finite Element Structural Liners option is now included at no additional charge.

Dynamic Analysis: 3DEC simulates the nonlinear response of a system (soil, rock, and structures) to excitation from an external (e.g., seismic) source or internal (e.g. vibration or blasting) sources.

Thermal Analysis: The thermal option in 3DEC allows the simulation of transient heat conduction.

User-Defined Constitutive Models: User-defined constitutive models (UDMs) can be written in C++ for both deformable block materials (zones) and any discontinuities (joints, faults, bedding, artificial surfaces) to calculate new stresses, displacements and strains, for a modified existing material model or a fully customized material behavior.

二、 3DEC的功能特性

3DEC is ideally suited to analyze potential modes of failure directly related to the presence of discontinuous features. Work with either discrete blocks, zoned continuum, or both.

3DEC provides 12 built-in zone material models, three built-in joint models, groundwater flow (solid matrix and joints), coupled mechanical-flow calculation, ground support structural elements, and a built-in scripting language (FISH) that can customize or automate virtually all aspects of program operation, including user-defined properties and other variables.

The software can be extended with four options (dynamic, thermal, Finite Element (FE) liners and blocks, and C++ User-Defined Constitutive Models) that are offered separately from the base program (see Options for more information).

3DEC offers a fully integrated development environment that includes: project management facilities, built-in text editor, automatic movie-frame generation, extensive plotting capabilities, and results monitoring.

General

• Analysis of jointed rock and blocky structures based on the Distinct Element Method (DEM)
• Built-in project management tools, text editor, automatic movie-frame generation, and extensive plotting capabilities,
• Ideal for modeling large movements and deformations
• Accurate simulation of fast rotating rigid blocks
• Blocks may be rigid or automatically zoned (tetrahedral and/or hexahedral) to make deformable blocks
• Optimized to solve problems requiring non-linear multi-physics
• 64-bit, double-precision calculations
• Multi-threaded algorithms with no CPU locks or additional CPU fees
• Includes groundwater joint fluid-flow
• Includes groundwater matrix (i.e., permeable solids) fluid-flow between fractures
• Fluid flow may be either uncoupled or fully coupled hydromechanical
• Proppant simulation in fluid-filled joints
• Built-in scripting languages, FISH and Python, provides powerful user-control to parameterize, analyze, review, and modify nearly every aspect of the simulation, even during cycling
• Track histories of model properties and results throughout the model to allow for comparison to actual monitoring and instrumentation data
• Updated commands that are intuitive, easy to learn, and easy to apply NEW
• Automatic conversion tool to translate 3DEC 5.2 data files to the updated 3DEC 7.0 syntax NEW

Materials and Constitutive Models

• Includes 12 built-in constitutive material models:
  • Elastic, isotropic
  • Elastic, transversely isotropic
  • Elastic, orthotropic
  • Drucker-Prager
  • Mohr-Coulomb
  • Ubiquitous-joint (UBJ)
  • Strain hardening/softening
  • Bilinear strain hardening/softening UBJ
  • Double yield
  • Modified Cam-clay
  • Hoek-Brown UPDATED
  • Hoek-Brown-PAC UPDATED
• Includes 8 built-in creep material models:
  • Classical (viscoelastic)
  • Burgers substance (viscoelastic)
  • Two-component power law
  • Reference creep formulation (WIPP model) for nuclear-waste isolation studies
  • Burgers-creep (viscoplastic; combination of Burgers and Mohr-Coulomb models)
  • Power-law (viscoplastic; combination of the two-component power law and the Mohr-Coulomb model)
  • WIPP-creep (viscoplastic model combining the WIPP model and the Drucker-Prager model)
  • Crushed-salt

• Includes six built-in joint material models:
  • Elastic
  • Mohr-Coulomb
  • Continuously Yielding
  • Softening Healing Mohr-Coulomb NEW
  • Bilinear Mohr-Coulomb NEW
  • Power Law Creep NEW
• Specify statistical distributions for material properties
• Groundwater fluid flow analysis is included
  • Effective stress, pore pressure (water table)
  • Steady-state
  • Transient
  • Fluid flow through fractures and matrix (blocks between fractures)
  • Fracture fluid pressure and matrix fluid pressures are also coupled
  • Mechanical-fluid coupling
  • Simulate the transport and mechanical effects of proppant fluid filled joints
• Three options are available for additional analysis:
  • Perform dynamic analysis by simulating earthquakes, vibrations, and blasts
  • Perform thermal analysis by simulating transient heat conduction
  • Create, load, and run customized (user-defined models) zone and joint models via C++ scripting

Model Construction

• Automatic mesh generation in fully deformable blocks UPDATED
• Build models directly from closed geometry surfaces (e.g. DXF): NEW
  • fill volume with tetrahedral blocks or
  • merge blocks to form zones within single closed surfaces
• Cut blocks with DXF geometry NEW
• Create blocks from VRML files NEW
• Built-in voronoi block generator NEW
• Built-in block zone densification for hexahedral and tetrahedral mesh refinement, including automatic octree generation from surfaces and volumes
• New grid file format for importing and exporting blocks and zones UPDATED
• Convert tetrahedral blocks into zones during import NEW
  • blocks with the same group name can be merged together to form multiple zones within a single block
  • this is 2-3x faster than joining
• Automatic tunnel region generator
• Beam, cable, and pile geometry can be imported from CAD data NEW
• Define groups using visual and property-based ranges UPDATED
• Built-in tools to statistically generate discrete fracture networks
• Import 3DEC grids created by the Griddle plug-in in Rhinoceros 3D CAD
• Block generation using primitives (face, tetrahedral, brick, drum, and prism)
• Wall-type blocks speed up model runs as motion and wall-to-wall contacts are skipped in solution cycles

Joint Sets and Discrete Fracture Networks

• Joint structures can be built into the model directly from geologic mapping
• Specify continuous and discontinuous joint sets by orientation, number or spacing, origin, and persistence
• Random seed values and statistical deviations can be utilized to create multiple realizations (examine sensitivities and risk)
• Blocks can be hidden (and subsequently restored, similar to a layer) to limit joint cutting or joining
• Easily define non-persistent joints (e.g., circular) and their properties
• Blocks can be cut using Discrete Fracture Network (DFN) geometry
• Incorporate Discrete Fracture Networks (DFNs) by specifying density (e.g., number of fractures per unit distance/area/volume) and orientation-, size-, and position-distributions for circular disks or polygons
• Import/export both Itasca circular disk or Fracman polygon DFN data formats

Boundaries and Initial Conditions

• Discontinuities (interfaces, joints, joint sets, and DFNs) are regarded as distinct boundary interactions between blocks; joint behavior is prescribed for these interactions
• Stress boundary
• Applied force (load) boundary
• Velocity boundaries along Cartesian axes and along a normal direction
• Structural elements for ground support include:
  • hybrid bolts NEW
  • beams
  • cables
  • piles NEW
  • shells NEW
  • geogrids NEW
  • liners (included; no longer an option) UPDATED
• Add external infrastructure (such as dams, bridges, walls, buildings, etc.) using finite element structures (included; no longer an option) UPDATED
• Time-varying boundary conditions
• Couple a detailed inner model to a larger far-field model for increased solution efficiency
• Define in-situ stresses and stress gradients
• Includes tools to easily transfer field stresses to model stresses
• Automatically assign in-situ stresses based on model surface topology, depth, material density, and stress-ratio values
• Quiet (i.e., non-reflecting) and free-field boundaries (with dynamic option)

FISH Scripting

• Provides powerful functionality to parameterize, analyze, review, and modify nearly every aspect of the simulation, even during model cycling
• Multi-threaded FISH for much faster iterative calculations NEW
• Built-in text editor provides command syntax error checking and context sensitive help for simpler, faster model generation UPDATED
• FISH management control set displays the current values of FISH variables, and functions, even during cycling NEW
• Intrinsic variables and functions (e.g., cos, round, inverse(matrix), clock, max, sqrt, urand, parse, cross, dot, pi, and more)
• Control statements (e.g., loop, loop-while, command, if/else-if, case, pause/continue, and more)
• The foreach object construct greatly simplifies FISH NEW
• Intrinsic email functions to automate model notifications and result delivery (e.g., attached plots, history CSV data, and parameter values)
• Even more variable types: Map, Matrix, Boolean, Symmetric Tensor, and Structures NEW
• Input statements to pass data to and from FISH functions
• Inline FISH (embed FISH calculations within a command)
• Extra variables for blocks, zones, gridpoints, contacts, and subcontacts permit user-defined parameters to be applied, computed, or measured for each of these data structures
• Blocks, zones, gridpoints, contacts, and subcontacts and be filtered by groups. Each data structure may be associated with multiple groups using group slots (similar to layers)
• Error handling functions
• Full FISH access to geometric data
• Model data can be exported as a binary or ASCII file for use in, or exchange with, third-party software
• Call functions at any stage of a calculation cycle (e.g., start of cycle, when contact created/detected, when sub-contact created/detected, and velocity input) using FISHCALL functions
• Learn more about FISH

Factor of Safety Analysis

• Automatic, fast solutions using the shear strength reduction (SSR) method and a converging bracket approach
• May include strength properties for certain zoned material models and the Mohr-Coulomb joint model
• Applicable for Mohr-Coulomb, Ubiquitous-Joints, Hoek-Brown, and Modified Hoek-Brown constitutive models
• Color blocks by excess shear stress or factor of safety for a given hypothetical set of joints

User Interface

• Common interface as Itasca's FLAC3D, PFC, and UDEC software
• Project file and project management tools simplify organizing data files, save files, plots, etc.
• Associated files in a project can be bundled together into a single file to easily share and archive work
• Multiple layout configurations and customization are possible
• Advanced ranging and filtering of model regions
• Built-in, advanced text editor with command and FISH context coloring
• Command-level UNDO: a record of all commands used to create a model is recorded in the SAV file, permitting the model to be rebuilt to the previous state
• Advanced methods of filtering objects (connected to interfaces, on model surface, and by object extent)

Post Processing

• Extensive visual plotting capabilities, including contouring on blocks, zones, and joint-surfaces; scalar, tensor, and vector plots, 3D isosurface contouring of gridpoint and zone data
• Cut-planes, clip-boxes, and transparency settings to assist with engineering analysis and high-quality results plotting
• Equal area and equal angle stereonet plotting of DFN joint orientations
• Equal angle stereonet plotting of joint normal orientations and orientations of major, minor, and intermediate principal stresses
• Export plots as PNG, DXF, VRML, SVG, or PostScript formats
• Results visualization (property/results painting) on DXF or STL geometry
• Easily export history results to spreadsheet-compatible CSV files
• Import and export tables, histories, and model variable data to ASCII files
• Automatically export a series of PNG images at regular cycle intervals to create a video-ready image set (third party software required for video assembly)
• Ability to export plot views as data files permits favorite views (orientation, plot-items, property settings, etc.) to be saved and restored in the same, or another, model
• Track and plot fragments (i.e., disconnected groups of blocks)

Responsive Help

• Documentation is now in HTML format NEW
• Access Help at the command prompt or within a data file [F1] NEW
• Access Keyword Help [? + Enter] at the command prompt to list the possible commands/keywords given the preceding command input
• Access Inline Help [Ctrl + Spacebar] to auto-complete commands NEW

三、 3DEC    7.0版新增功能



1.   建模新工具

Many new tools have been added to 3DEC 7.0 to simplify and speed-up both rigid and deformable (zoned) model construction.

Working with Geometry

3DEC models can consist of rigid and deformable (zoned) blocks. Automatic mesh generation in fully deformable blocks now uses the same advanced meshing libraries as Griddle. This provides both faster meshing and greater control on the size, gradation, and quality of 3DEC zone meshes. It also makes it possible to automatically build models directly from geometry.

Geometry can be used to construct models as follows.

• Build models directly from a single, closed geometric volume by filling it with tetrahedral blocks using the BLOCK GENERATE BY-GEOMETRY command.
• Tetrahedral blocks may be converted into zones by adding the MERGE keyword to the previous command.
• Blocks with the same group name can be merged together to form multiple zones within a single block. This approach is 2-3 times faster than using the JOIN command.

• Blocks may be cut using geometry to create more complicated block shapes. Each facet of the geometry surface represents a “joint” and cuts any blocks that it touches. In this way, almost any geometric shape can be cut into a 3DEC model.

• Blocks can now be created by importing convex, closed solids using the Virtual Reality Modeling Language (VRML) 2.0 file format. This is particularly useful for modeling masonry structures.

• Beam, cable, and pile structural elements can be imported from geometry. Design your ground support layout in Rhino 3D, or another CAD tool, and easily import it into 3DEC.

3DEC can import geometry, or geometric data*, from these data file formats.

• AutoCAD drawing interchange (DXF)
• Stereolithography (STL)
• Itasca geometry (GEOM**)

Voronoi Generator

Generate models using random Voronoi blocks that can fill a single, closed, convex volume defined by a geometric set. Voronoi blocking is particularly useful to simulate crack propagation with damage (fracturing) progressing as the joint strength between Voronoi blocks is exceeded.

The Voronoi algorithm randomly distributes points on, and within, the geometric set. Voronoi blocks are created by constructing perpendicular bisectors of all segments of the Delaunay triangulation created between all seeds. The blocks are truncated at the boundaries of the geometric set. The distance between two seeds can be controlled using the MAXIMUM-EDGE and MINIMUM-EDGE keywords.

 

Importing and Exporting Models

• A new 3DEC 7 binary file format makes it easier and faster to import and export blocks and zones. An ASCII file format is also available.
• Export 3DEC zones and joints to files for creating FLAC3D 7 zones and interfaces.
• Export 3DEC blocks/zones to rigid blocks in PFC 6.
• Export sections (along a specified cut-plane) of 3DEC rigid blocks to UDEC 7 models.

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*3DEC has the capability to import and define arbitrary geometric data (i.e., CAD data) as collections of connected polygons, edges, and nodes. Polygons are defined by a series of edges, and edges are defined by two nodes. Geometry data can also be created and modified in 3DEC via commands or scripting and used in plots as a filter (range logic) or for visualization (as a reference image or for data painting/contouring).

**An Itasca-defined format (*.geom) that preserves additional metadata (e.g., group names, FISH extra variables, etc.). Both ASCII text and binary formats are available.

2. 使用者新介面


The user interface in 3DEC 7 is incorporated in Itasca's common framework layout and structure. If you've used FLAC3D 7's interface, you've already used 3DEC 7. The following video demonstrates how to create plots and add plot items in 3DEC 7.

General

• Expanded startup dialog for important notifications and recent project files.
• New control set displays global FISH symbols and values, including during cycling.
• Streamlined File menu items. Facilitation of model import (from 3DEC 7, Griddle, or geometry) and export (to 3DEC 7, FLAC3D 7, PFC 6, and UDEC 7).

Help and Documentation

• Access responsive HTML documentation via the F1-key based on the mouse cursor position in the command prompt or within a data file.
• Documentation is available in a built-in pane.
• Documentation may also be viewed in the system default browser. Use of the built-in pane or system browser is set by user preference.
• Access Inline Help [Ctrl + Space bar] to auto-complete commands.
• Copies of 3DEC 7, FLAC3D 7, and PFC 6 documentation are available on our website at http://docs.itascacg.com.

Plotting

• Simplified plotting via labels (groups, materials, material models, state, properties, etc.) or contours (displacements, stresses, velocity, temperature, etc.).
• Attributes for the active plot item now shown below plot item list.
• Reorder, copy, and, paste plot items in the plot item list interactively.
• Copy and paste plot items between plots.
• Synchronize plots via a keyword. Changes to the plot view in one plot are applied automatically to any synced plots.
• Use preset plot views and add your own views.
• Copy and paste plot view data.
• All quantities can now be contoured (e.g., stress and strain).
• Most plot items include the ability to map to other coordinates and the ability to plot with exaggerated deformation to highlight large displacements in small strain models.

3.  新的節理模型

Softening-Healing Mohr-Coulomb Joint Model

The Mohr-Coulomb joint model has the following deficiencies when used to model seismicity in jointed models.

1. The stress drop is instantaneous when slipping starts — shear strength drops instantaneously from a peak to a residual value. This means that all slip events are seismic (see figure below).
2. Once slip has occurred, there is no way for the strength on the fault to recover back to the peak value. This means that stick-slip behavior is not possible.

For modeling seismicity, the Softening Healing Mohr-Coulomb model is now available. It is based on the standard Mohr-Coulomb model with two additions.

1. When the joint starts slipping, the shear strength (e.g., cohesion and friction) evolves from the peak value to the residual value over a user-specified critical slip distance Dc.
2. When slipping stops, the shear strength recovers instantaneously to the peak value.

There is no softening or healing for the tensile forces. The tensile strength drops instantaneously when the strength is exceeded (i.e., no softening) and the tensile strength remains at the residual value (i.e., no healing). Dilation (ψ) behaves in the same way as cohesion or friction.

For a non-slipping joint, the value of cohesion and friction are the peak values. When the strength is exceeded, the strength is a function of the slip distance. When the slip distance exceeds the critical slip distance, the residual values of cohesion and friction are used. Two formulations, linear and non-linear, for the evolution of shear strength are available. For the non-linear formulation, an exponent (α > 1) dictates the severity of the strength drop.

Bilinear Mohr-Coulomb Joint Model

The Bilinear Mohr-Coulomb Joint Model has two different shear strength envelopes. The failure envelope changes when a critical level of normal stress is exceeded. By default, the normal stress threshold is automatically calculated at the intersection of the two failure envelopes, but the user may override this default and specify any value.

Both the peak and residual shear strengths can have bilinear envelopes and there may be different normal stress thresholds for the peak and the residual. It is also possible to specify two different values of dilation, such that dilation angle changes when the residual normal stress threshold is exceeded. If a dilation angle for the high normal stress (ψ2) is not given, its value defaults to the dilation of the low stress region (ψ1).

Power Law Creeping Joint Model

The creep behavior in a discontinuity is of a different nature depending on the joint surface (planar or rough) and on the filling material (gauge).

1. In unfilled discontinuities, two mechanisms can be distinguished, depending on the joint surface characteristics.
   1. In planar joints, the creep displacement is controlled mainly by an adhesion-frictional mechanism [Bowden and Curran 1984].
   2. In rough joints, the creep displacement is due to stress concentrations at asperities that cause slip as the asperities yield progressively and the shear stresses are redistributed to other intact asperities [Schwartz and Kolluru 1982, Ladanyi 1993].
2. Rock joints may naturally be filled with frictional or cohesive material, which is usually of a poor quality. In this case, the creep is controlled mainly by the characteristics of the filling material [Höwing and Kutter 1985, Malan et al. 1998].

To simulate creep due to the filling material, 3DEC uses an adaptation of Norton’s law — commonly used to model the creep behavior of soft rocks subjected to a shear load — for the joint elements.

The Power-Law-Creep joint model in 3DEC is characterized by a visco-elasto-plastic behavior in the shear direction and an elasto-plastic behavior in the normal direction. The visco-elastic and plastic elements are assumed to act in series. The visco-elastic behavior corresponds to a Norton’s law. The plastic behavior corresponds to a Mohr-Coulomb joint model.

4. 指令及FISH的更新加強

Documentation Support and Help

To make it easier for experienced users to start using version 7, the following support is provided.

Mapping

Program documentation provides lists that map 5.2 commands to 7.0 commands (see 3DEC 5.2 to 7.0 Command Mapping). A few examples are shown below.

CONFIG dynamic	-->	model configuration dynamic
CYCLE	-->	model cycle
FIX xvel	-->	block fix velocity-x
GENERATE	-->	block zone generate
INITIALIZE xdisplacement	-->	block gridpoint initialize displacement-x
ZONE density	-->	block zone property density

Similar maps relating 5.2 FISH to 7.0 FISH (see 3DEC 5.2 to 7.0 FISH Mapping) are provided. There will not necessarily be a direct mapping of old to new function arguments nor of return types. 3DEC 7.0 takes advantage, on occasion, of the new types available in FISH (tensors, matrices, etc.) to streamline FISH intrinsics. A few examples are shown below.

b_area	-->	block.area
z_state	-->	block.zone.state
urand	-->	math.random.uniform
code_majorversion	-->	version.code.major
udv_create	-->	data.vector.create
face_nx	-->	block.face.normal.x

Enhanced Documentation and Help

• Contextual help: Press F1 when your cursor is over a command or FISH function to access the reference documentation for the item.
• Intelligent command completion (inline help). Use Ctrl+Space while typing a command to see and insert the next keyword from a list of those possible at the current cursor position.

 

Automatic Conversion Tool

An automatic file conversion tool called "3DEC Command Conversion..." is available on the Edit menu.

Before doing the conversion, a back-up copy of the file will be made in a folder called “pre-conversion” in the same directory as the data file. The data file will be converted on-disk and then reloaded into the text editor.

There are cases where the conversion tool cannot translate a version 5.2 command to version 7.0. In these cases, the problematic portion of the command in question will be surrounded by “%%” symbols in the data file and highlighted in orange. When available, explanatory information will appear, commented and also highlighted in orange. These commands require manual editing to complete conversion. TIP: place the cursor in the line with problem command and press F1 to directly access help for that command.

Two examples are demonstrated in the following video (請參考原廠網站https://youtu.be/XOc-_ZYr27g)