FLAC3D Features

FLAC3D offers a fully integrated numerical modeling environment that includes model project management capabilities, interactive mesh building and model construction, run-time monitoring of results (including FISH scripting variables and function states), extensive plotting options, and easy, automatic movie pre-processing tools. While FLAC3D has been developed to be general in nature, it has been designed, in collaboration with our own consultants, with geotechnical and geomechanical applications in mind for civil (tunnels, rail embankments, wharfs, soil enhancement, retaining walls, piles, foundations), mining (ramps and drifts, stopes, blasting, subsidence, caving, sills, pillars, tailings dams), oil & gas (salt caverns, wellbore optimization, borehole breakouts, compaction/subsidence, cap rock integrity), and power generation (dams, power house caverns, wind turbine foundations). FLAC3D can be extended with options that are offered separately from the base program.


  • Large-strain simulation of continua
  • Explicit solution scheme
  • Extensive solution controls and options
  • Multi-physics modeling
  • Multi-threaded solutions for mechanical calculations with no CPU locks or additional fees
  • Fluid flow, thermal (optional), and attach-logic are multi-threaded to perform much faster NEW
  • 64-bit version
  • All commands have been reformulated to be more consistent across Itasca software, more intuitive in construction, and easier to learn and apply using a syntactical pattern of noun-verb-option-modifiers-range.
  • FISH, FLAC3D's built-in scripting language, permits access (read) and control (write) of most model parameters, even while cycling, and has been updated for consistency and improved ease-of-use
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  • Assign model objects (zones, gridpoints, faces, structural elements, etc.) to groupsvia the Model pane
  • Assign constitutive and material properties via the Model pane NEW
  • Model objects can belong to multiple groups by assigning groups to slots (akin to CAD layers)
  • Groups can be assigned interactively using a number of visual ranges (cylinder, sphere, position, etc.) and property-based ranges (group, ID list, surface, orientation, etc.) through the Model Pane
  • Track histories of model properties and results throughout the model to allow for comparison to actual monitoring and instrumentation data
  • All files associations (data, saved states, results, CAD geometry), plots, preferences, and settings are contained with a single project file
  • Project files and associated files (excepting saved states) can be bundled into a single file for easy distribution or project archiving
  • Any event (via the user interface, commands, or FISH scripting) that modifies the model state is recorded, permitting both undo and archiving functionality and allowing replay or reuse any event or the entire modeling process
  • Coupled hydro-mechanical-thermal effects using socket commands and FISH scripting
  • Custom "extra" variables can be assigned to and read from nearly every model part (e.g., zones, faces, gridpoints, interfaces, structural elements, etc.)
  • Results files store a user-selected subset of model data (e.g., histories, zones (stresses, displacements, groups, etc.), FISH, geometry, structural elements (forces, displacement, velocities, etc.) from the current saved model state, permitting for much smaller files for archiving, distribution, and post-processing purposes.


  • Create models from primitive shapes using parametric commands (e.g., <strong>brick, cylindrical-shell, cylinder, cylindrical-intersection, degenerate-brick, pyramid, radial-brick, radial-cylinder, radial-tunnel </strong>(parallelepiped), <strong>tetrahedron, tunnel-intersection, uniform-wedge, </strong>and<strong> wedge</strong>
  • Automatic octree mesh generation from geometric surfaces and volumes
  • Extrude zones from a topography (DXF surface)
  • Building Blocks, an interactive means of building structured meshes as blocks in 3D
    • Import CAD data (DXF and STL formats)
    • Interactively assemble a series of connected blocks
    • Objects can be snapped to locations, other objects, or imported geometry
    • Object points may be merged
    • Add new blocks or block layers to existing block faces; roll the mouse wheel to select from a range of block types
    • Block, face, edge, and gridpoint manipulation includes position, scale, rotate, and limit
    • Block refinement operations include splitting, hiding/showing, cutting, copying, and pasting
    • Interactive control of grid ratio and density, and edge curvature (line, arc, and circular)
    • Automatic block quality checking
    • Automatic zoning based on some target zone length, model resolution (extent), or total number of model zones
    • Drape blocks to conform onto an imported geometry
    • Basic KUBRIX Geo functionality bulit-in: generate hexahedron or tetrahedrons (split into hexahedron blocks) from an imported geometry
    • Import from a library building block sets
    • Export user building block sets to the library
  • Built-in 2D extruder
    • automatic hexahedral, hex-dominate, and tetrahedral 2D meshing
    • is integrated seemlessly with both Building Blocks (for further 3D manipulation) and the Model Pane (for direct use)
    • the extrusion data are also accessible by FISH, which means that an extruded geometry can be scripted and parameterized
  • Import ABAQUS and ANSYS ASCII meshes
  • Includes the BlockRanger plug-in (requires a valid Rhinoceros 3D CAD license)


  • Can interactively view, select, and operate on model objects
  • Quickly assign zones and faces to groups and slots for easy application of subsequent commands and FISH functions
  • Hide/show, delete, and recolor group zones and faces
  • Assign constitutive models interactively
  • Interactive zone densification (increase zone resolution for a region)
  • Use a plane defined by a break angle to make zone face selection easily on simple, or even complex, surfaces
  • Automatic skinning tool to name internal and external boundaries via a break-angle setting
  • Boundary conditions are much easier to work with since faces are easy to select and group
  • Create geometric data directly from zone faces
  • Disambiguate tool for identifying all groups associated with a zone or face


  • Includes 21 standard, built-in material constitutive models:
    • Null
    • 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
    • Modified Hoek-Brown
    • CYSoil
    • Simplified CYSoil (CHSoil)
    • Caniso NEW
    • Plastic Hardening (PH) UPDATED (small strain)
    • Mohr-Coulomb Swelling
    • Mohr-Coulomb Tension
    • NorSand NEW
    • Soft-Soil NEW
  • Groundwater analyses are included at no additional cost
    • Effective stress (water table)
    • Steady-state flow
    • Transient flow
    • Couple fluid flow analysis to mechanical model (two-way coupling) as well as to optional dynamics and thermal analyses
  • Specify property statistical distributions
  • Built-in tools to generate Discrete Fracture Networks (DFN) and assign properties to interfaces and/or intersecting zones NEW
  • C++ Plugin option available to create powerful, custom C++ function DLLs and user-defined constitutive models (UDMs)


  • Six forms of structural-support members can be specified for ground support:
    • Beam
    • Cable
    • Pile
    • Shell
    • Geogrid
    • Liner
  • Each of these members can be joined to one another and/or the grid
  • 2D structural elements (shells, geogrid, and liners) can be interactively defined using the Model Pane
  • Structural element geometry can be imported from CAD software via DXF or STL files


  • Displacement and stress boundaries
  • Artificial boundaries
  • Water table for effective stresses
  • Interfaces allow inclusion of faults, joints, and boundaries that permit slip, separation, and closure
  • Automatic zone relaxation
    • Gradually 'excavates' materials by reducing the stiffness, stresses, and densities of the zones until the excavation is partially- or fully-relaxed
    • Useful for creating ground reaction curves (GRC)
    • Avoids spurious inertial effects in the static solution process from causing unrealistic damage to the region around the excavation (due to very weak materials and/or high stress fields)
  • apply logic has been completely rewritten to be more automatic and for improved plotting
  • Easier local system velocity boundary conditions
  • Westergaard approximation (i.e., hydrodynamic water pressure represented by a parabola) for dynamic analysis with water. This approach is widely used for preliminary calculations of the hydrodynamic pressure on dams and spillway gates
  • Locally applied FISH multipliers – vary apply commands in space and time


  • Data files (commands and/or FISH scripting) included within projects make batch processing, model parameterization, and complex construction sequencing straightforward
  • Mechanical and fluid flow calculations are multithreaded
  • Groundwater flow calculations are included as a standard feature
  • Coupled calculations between standard (mechanical and fluid flow) and options (thermal, creep, C++ Plug-in, and dynamic)
  • Built-in, automatic Factor-Of-Safety solution (see next topic)
  • solve elastic command for initial elastic equilibrium state extended to most plasticity constitutive models
  • Seismic wizard for pre-processing ground waves for optional dynamic analysis


  • Automatic, fast solutions using the shear strength reduction (SSR) method and a converging bracket approach
  • Include groundwater, structural support elements, and material strength properties for zones and interfaces
  • Applicable for Mohr-Coulomb, Ubiquitous-Joints, and Hoek-Brown constitutive models
  • Exclude one or more factors (e.g., cohesion)
  • Associated plastic flow rule (i.e., dilation) can be enabled
  • Safety map contouring FISH function is provided to estimate and visualize the distribution of factors of safety throughout the model


  • FISH is a scripting language for FLAC3D that enables the user to define new variables and functions
  • FISH functions may be used to extend FLAC3D or add user defined features (e.g., servo-control boundaries may be applied to a numerical test, unusual property distributions specified, and parametric studies automated)
  • Improved to make function syntax clearer and more consistent for more intuitive scripting and ease of use
  • Includes a powerful, built-in text editor
  • FISH is now multi-threaded for faster execution and has new functionality to loop through any objects (zones, faces, extra variable,
    etc.) for additional performance improvements NEW
  • Includes a FISH management control set that displays the current values of FISH variables and functions (including while model is cycling)
  • Text editor includes a built-in conversion tool to translate FLAC3D 5.0 data files to the new FLAC3D 6.0 format
  • Integer, floating-point, and string data types that are automatically assigned and reassigned based on value
  • Both local and global variables can be specified
  • Control statements includecase, if-else-endif, exit, loop, loop while, section, and command
  • Built-in error handling
  • Use fishcall to access information at any point during the solution cycle (e.g., before any structure calculations or after the motion calculations) for each solution cycle or step
  • Built-in general scalar, vector, tensor variables and intrinsic logic, mathematic, geometric objects, text, and parsing functions
  • Access FLAC3D solution variables, zone, and gridpoint variables (including zone strains and strain rates), and constitutive model variables
  • Access data tables, arrays, ASCII/binary data, I/O routines, data structures, and memory
  • Access socket I/O routines to exchange data between two or more licensed Itasca codes (FLAC3D, 3DEC, or PFC3D) running as separate processes
  • Includes FISH Library functions (e.g., automatically generate FOS contours, vary some slope angle iteratively to reach a given factor of safety)


  • Multiple plot export formats (PNG, DXF, VRML, PDF, SVG, and PostScript)
  • Save plot pane settings as views within the project or export these as binary or ASCII data files in order to save and reuse custom plots between projects
  • Extensive plot item ranges (interactive/visual and property-based) for filtering the model (e.g., geometry offset, position, geometric shapes, orientation, ID, group, state, etc.)
  • Extensive visual plotting facilities for zones, faces, fractures, structural elements, and user-defined data
  • Plot items include axes, boundary conditions, contours, Factor Of Safety, history locations, iso-contours, labels, particle trace, scalebox, tensors, tracked particles, vectors, water table, etc.
  • Available contour/iso-contour plots include acceleration, condition, convergence, density,displacement,effective stress, extra variables, fluid properties, mechanical properties, pore pressure, saturation, strain increment, strain rate, stress (axial, principal, volumetric, max. shear, total, Von Mises equivalent, Octahedral shear, norm, and mean),stress-strength ratio, temperature, thermal properties, velocity, etc.
  • Charts include XY tables, histories, profile lines, rosettes, and stereonets
  • Export tables, histories, and model variable data as spreadsheet-compatible CSV files
  • Query the values of a model variable at arbitrary locations in space (field data) and paint field data onto imported geometry
  • Automatically create a video-ready series of images/frames exported at regular intervals during cycling (or after modeling using results or saved files); third party software required for video assembly

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