We got on at the ground floor. From that vantage point, numerical modeling has become an increasingly important and increasingly utilized tool for understanding the behavior of the earth in response to the engineering efforts of man. I urge you to get on at the ground floor and plan to participate in the 2nd FLAC/DEM Symposium (see the information below). The conference provides a one-of-a-kind chance to see how Itasca's consulting work and the work done with our software by our customers define the state-of-the-art in numerical modeling.

– Loren Lorig, Chief Executive Officer


Modeling of Large Deformations in Tunnels

Recent tunnel modeling work performed by Itasca Consultores S.L. (Oviedo, Spain) has dealt with the case where, when large stress/strength ratios are present, tunnels in weak ground present a squeezing behavior that translates to constant closure rates far from the tunnel face. It is not always possible to reproduce this behavior with conventional elastic-plastic constitutive models (below left). Reducing the stiffness of the ground usually produces abnormally large deformation far away from the tunnel. Reducing the strength of the ground in the model can incorrectly produce tunnel collapse at a low deformation level relative to the real deformations (adjacent figure).

For these cases, often it is necessary to use a creep constitutive model (cpow in this case) that introduces a shear strain rate that depends on the deviatoric stress invariant. With this constitutive model it has been possible to calibrate the evolution of the deformations of the heading phase (below right) and then to simulate the behavior of the tunnel in a future phase (the support of the bench phase, the invert or the lining in a long term).

Left: comparison between measurements and simulation with Mohr-Columb constitutive model; Right: Calibration of the heading phase with cpow constitutive model

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The pre-release of Enhanced Visualization (EV) for PFC3D will be available in May 2010. In addition to supplying blazingly fast OpenGL-based 3D graphics, EV provides access to project management, data file editing, and all-new visualization tools. A demonstration version of the program will be available at the time of the public pre-release.

Screen shot of the alpha version of EV; click here or on the image to enlarge in a separate window

Update Alert:
Current Versions
updated since
January 10, 2010:

A pre-release of UDEC 5.0 will be available in mid-May. The first major upgrade to UDEC in five years, this version benefits from several years' worth of developments in the GIIC (Graphical Interface for Itasca Codes) that is used by FLAC and UDEC. In addition, the code features a range of enhancements to its modeling capabilities. Complete information on all the new features of this version will be made available on our web site as the time of the pre-release draws nearer.

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Introducing Itasca India Consulting Private Limited

Itasca is pleased to announce that the formal establishment of its office in India is complete. The new company, Itasca India Consulting Private Limited, is located in Nagpur, India. The office is led by Jay Aglawe, a mining engineer* with over 16 years of experience consulting in India. The office will open officially for business in the very near future and, in addition to working primarily in the in area of hydro-electric power schemes, will serve as the sales office for Itasca software in India.

*In the previous edition of Groundworks, Jay was mistakenly
designated a civil engineer. Our apologies to Jay for the error.


New Leadership Personnel at
Itasca Consulting Group, Inc. (ICG)

In January, Doug Stearley assumed the position of Financial Manager of ICG. Doug arrives with more than 30 years of experience in management and the financial administration of various industries, including process engineering, business acquisition, and consulting. He has a B.S. degree in Mechanical Engineering and an MBA.

Dr. Will Pettitt has accepted the position of General Manager at ICG. Will has served as principal geophysicist at ASC since 2003, and brings a strong background in geophysics, software, consulting and management to the general manager position at ICG. His presence will accelerate the integration of microseismic observation and numerical modeling technologies that began last May when ASC became a part of Itasca. During and after the transition to his new position he will continue to contribute to geophysics work being done at ASC. Will expects to assume his duties as GM in late spring.

The staff in Minneapolis is happy to have Doug and Will on board.

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The first spring training course is on FLAC, and it is a little more than one month away. The course on FLAC has 6 remaining spaces. There are only 3 remaining spaces for the FLAC3D course. The other courses are filling up as well. Registrations are accepted on a first-come, first served basis, so if you are planning to join us, sign up now. The complete schedule of classes is:

   FLAC Apr 12-14, 2010
   FLAC3D Apr 19-21, 2010
   KUBRIX Apr 22-23, 2010
   UDEC Apr 26-28, 2010
   3DEC May 3-5, 2010
   PFC May 10-13, 2010

Full course descriptions, registration, and price information are available online.

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2nd FLAC/DEM Symposium Update

Charles Fairhurst and Peter Cundall will be the keynote speakers at the 2nd International FLAC/DEM Symposium, 14-16 February 2011 in Melbourne, Australia. Visit www.flacdemsymposium.com for background on Dr. Fairhurst and Dr. Cundall. Also note: the deadline for submission of abstracts is April 30 — less than six weeks from now. If you are intending to submit an abstract, don't wait. Abstracts of 300 words or less should be sent to: Michele Nelson (mnelson@itascacg.com) at Itasca Consulting Group, Inc.

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Jiang, A., Z. Zheng, X. Zhou and Y. Han. (2009) "A Strain-Softening Model for Drilling-Induced Damage on Boreholes in Williston Basin," in Asheville 2009 (43rd U.S. Rock Mechanics Symposium/4th U.S.-Canada Rock Mechanics Symposium, Asheville, June 2009). Paper No. ARMA 09-26.

Pettitt, W. et al. (2009) "Using Continuous Microseismic Records for Hydrofracture Diagnostics and Mechanics," in SEG Houston 2009 (Proceedings, SEG International Exposition and 79th Annual Meeting, Houston, October 2009), pp. 1542-1546.

Reyes-Montes, J. et al. (2009) "Microseismic Analysis for the Quantification of Crack Interaction During Hydraulic Stimulation," in SEG Houston 2009 (Proceedings, SEG International Exposition and 79th Annual Meeting, Houston, October 2009), pp. 1652-1656.

Reyes-Montes, J. et al. (2009) "Application of Relative Location Techniques to Induced Microseismicity from Hydraulic Fracturing," in ATCE2009 (Proceedings, SPE Annual Technical Conference and Exhibition, New Orleans, 2009). Paper No. 124620.

Turichshev, A. et al. (2009) "Ground Support Audit at Brunswick Mine — Data Collection and Results Management," in RockEng 09 — Rock Engineering in Difficult Conditions (3rd CANUS Rock Mechanics Symposium/20th Canadian Rock Mechanics Symposium, Toronto, May 2009, M. Diederichs and G. Grasselli, Eds. Paper No. 3991.

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