FLAC3D (Fast Lagrangian Analysis of Continua in 3 Dimensions) is numerical modeling software for geotechnical analyses of soil, rock, groundwater, constructs, and ground support. Such analyses include engineering design, factor of safety prediction, research and testing, and back-analysis of failure.

Continuum analysis can be applied to engineering design of civil, mining, and geotechnical excavations (e.g., slopes, tunnels, caverns, stopes, etc.) and constructs (dams, foundations, footings, walls, etc.) in soil, intact rock, and rock masses (i.e., heavily jointed rock). Using interfaces, FLAC3D can also simulate discontinuities such as faults, joints, bedding planes, and engineered boundaries along constructs.*

FLAC3D utilizes an explicit finite volume formulation that captures the complex behaviors of models that consist of several stages, show large displacements and strains, exhibit non-linear material behavior, or are unstable (including cases of yield/failure over large areas, or total collapse).

Perpetual, monthly lease, and annual lease licenses are available as either a local USB-key (which is portable) or a multiple-seat network USB-key. Academic institutions qualify for special pricing discounts.


  • Nineteen built-in constitutive material models: the "null" model, three elasticity models, and fifteen plasticity models
  • Ground water flow analysis and multi-core processing is included at no additional cost
  • New built-in meshing tools for fast model generation and CAD interoperability
  • New selection tools let you interactively
    • Assign groups for defining material properties or excavation stages
    • Select surfaces to define boundaries and add liners
  • Automatic Factor of Safety analysis using the Shear Strength Reduction method
  • FISH, a powerful built-in scripting language for model customization, automation, and parametrization
  • No annual maintenance fees or CPU limits


  • Dynamic option for analyzing earthquakes, seismicity, and mine rockbursts, for example
  • Thermal option for analyzing both conduction and advection in materials for nuclear waste disposal and cement hydration, for example
  • Creep option for analyzing time-dependent material behavior, for excavations in salt or potash, for example
  • C++ Plug-in option for building powerful custom functions and constitutive models; Itasca maintains a library of user-defined models online


*Try 3DEC for simulations in blocky ground or if there are many more than 20 discrete faults, joints, or bedding planes in your numerical model.