What Are Extreme Deformations?

In the world of standard engineering problems, we often deal with small strains. However, “extreme deformation” refers to a material response that is highly nonlinear, involving significant changes in geometry and rigid-body rotations. We are talking about scenarios where strains exceed 10%—often reaching much higher levels. Why does this matter? In geoengineering, we often need to go beyond simple Factor of Safety of Probability of Failure calculations. To truly understand the behavior of landslides, tailings dam failures, or soil, we must model the consequences of failure, including run-out analysis, by understanding the complete evolution of an earth structure from stability to large-scale movement.

What Solutions does ITASCA Offer?

Standard FDM or FEM continuum tools (like FLAC2D and FLAC3D) in small-strain mode are generally valid only for strains around 1-2%. While a large-strain mode exists in ITASCA software, models may face a “High Mesh Risk”; as materials deform excessively, elements can invert or become highly distorted, leading to a loss of accuracy or solver failure. To address mesh distortion in continuum modeling, ITASCA is introducing an Automatic Remeshing (BETA) feature in FLAC2D v9.6, arriving in December 2025. This feature automatically detects distorted elements and automatically remeshes the grid, allowing simulations to continue accurately even under large strains without the grid quality degrading.

For scenarios where materials transition from solid to fluid-like flow (such as avalanches or scour), the Material Point Method (MPM) offers a powerful hybrid solution. New tools like MPoint3D and MPoint2D (also available as new BETA software with the release of v9.6 ITASCA Software) eliminate mesh risk entirely by resetting the grid every step while points carry the history. This method excels at handling extreme deformations like mixing and material flow.

Finally, for problems that are inherently discontinuous—like rockfall, cave mining, or granular flow—DEM tools (3DEC, UDEC, PFC3D, PFC2D) remain the gold standard. Because these methods simulate particles or blocks moving freely without a mesh, they naturally handle separation and flow, albeit at a very high computational cost due to contact detection.

Deformation Spectrum Diagram

Looking Ahead

The evolution of ground behavior modeling is about choosing the right tool for the complexity of the problem. Whether you need the speed of a continuum model or the granular detail of a discrete model, or something in between, ITASCA’s toolbox continues to expand.