Symposia

The first international FLAC Symposium on Numerical Modeling in Geomechanics was held on September 1-3, 1999. Over 90 participants from 22 different countries came to Minneapolis to attend the conference. The event originated as a celebration of FLAC's 15th birthday and as recognition of the code's popularity. In addition to the three-day symposium, activities available to participants also included a FLAC short course taught by Peter Cundall, a river cruise along the Mississippi, and a banquet held at the Nicollet Island Inn.

The FLAC Symposium was the the first time that a large group of users assembled to describe and discuss the wide variety of problems to which FLAC (and FLAC3D) may be applied. Symposium sessions covered engineering applications and theoretical developments in topic areas that included embankment and slope stability, underground cavity design and mining, dynamic analysis, soil/structure interaction, coupled processes and fluid flow, failure and collapse analysis, nuclear waste isolation, and constitutive models. Development plans for the codes were discussed, including the GIIC (Graphical Interface for Itasca Codes). The topics of the symposium and a brief overview of the history of FLAC are contained in the symposium proceedings, FLAC and Numerical Modeling in Geomechanics, edited by symposium organizers Roger Hart and Christine Detournay.

The creep option can be used to simulate the behavior of materials that exhibit creep - i.e., time-dependent material behavior. Six creep models have been implemented in FLAC. These are:

• a classical viscoelastic model;
• a two-component power law;
• a reference creep formulation (the WIPP model) for nuclear-waste isolation studies;
• a Burger-creep viscoplastic model combining the Burger's creep model and the Mohr-Coulomb model;
• a WIPP-creep viscoplastic model combining the WIPP model and the Drucker- Prager model; and
• a crushed-salt constitutive model.

The first model is the classical formulation known as the Maxwell substance. The second model can be used for mining applications (e.g., salt or potash mining), and the third model is commonly used in thermomechanical analyses associated with studies for the underground isolation of nuclearwaste in salt. The fourth model expands on the first model and also includes aKelvin and a Mohr-Coulomb component. The fifth model is a variation of the third model and includes a Drucker-Prager plasticity component. The sixth model is also a variation of the third and includes volumetric and deviatoric compaction behavior.

The two-phase flow option in FLAC allows numerical modeling of the flow of two immiscible fluids (with optional capillary pressure) through porous media. The formulation applies to problems, such as those encountered in reservoir simulation, in which a fluid displaces another and simultaneous flow of the two fluids takes place in the porous medium with no mass transfer between them. The option uses built-in pressure and permeability laws (of the van Genuchten form), and an explicit finite difference solution scheme with upstream weighting.

The Fourth International FLAC Symposium, held May 29-31, 2006, in Madrid, was a success. Attendees had the chance to hear over 50 papers on the use of FLAC and FLAC3D in the areas of: slopes and embankments; underground structures; coupled processes and fluid flow; dynamic analysis; soil-structure interaction; tectonics; numerical techniques; and constitutive models/material behavior. We would like to thank all who attended for a truly memorable experience.

If you did not have the chance to attend the symposium, you can still find out what you missed by getting the Symposium Proceedings and/or the Symposium Presentations. The Proceedings CD is available for purchase from Itasca Consulting Group. The Presentations CD is available free on request (shipping charge is applied).

Itasca hosted the first-ever FLAC/DEM Conference from August 25-27, 2008 in Minneapolis. The conference featured topics and discussions covering the spectrum of Itasca software: FLAC, FLAC3D, UDEC, 3DEC, PFC2D, and PFC3D. Where past Itasca-sponsored conferences limited their scope to a single 2D/3D code pair, this conference, in considering all the codes, offered a complete look at the state of numerical modeling with Itasca software.

A Proceedings CD order form will be available shortly. Presentations from the symposium will also soon be available on this web page, free of charge.