August 2006
This space frequently is devoted to a message from John Markham, Chief Executive of HCItasca. However, in this issue I'd like to pass along a message that John would never write himself. Itasca Consulting Group, Inc. celebrates its 25th anniversary this year, and John has been with us from the start. Congratulations and thanks to John for his leadership through our first quarter century.
—Roger Hart, Director of Software Services
Analysis of Geogrids' Efficiency to Prevent the Local Collapse of a Road
Road developers have taken advantage of underground mine closures in northeastern France to locate new roads on top of ancient mines. This raises the problem of possible road deformation as a consequence of a collapse at depth. Road builders particularly fear the formation of a "step" on the road. To prevent this from occurring, they may incorporate geogrids in the layers located beneath the road. However, no "state of the art" is available to inform the design of such reinforcements. Engineers at Itasca Consultants, S.A.S. (ICSAS) used FLAC to assess the geogrids' efficiency and check the load they would incur.
Because geogrids are highly anisotropic, two orthogonal layers are used. The collapse at depth was simulated by applying a controlled downward velocity to part of the base of the model, resulting in the development of a vertical, 12 cm high, "step" at the base. ICSAS studied the impact of the orientation of the step with respect to the geogrids' orientations in order to detect the most dangerous configuration. The results show that, in all cases, geogrids attenuate deformations and widen the zone along the surface on which they develop. Because the resulting road profile has a maximum slope under 7% (acceptable), the model validates the design proposed by the geogrids' manufacturer.
The figure at right shows distribution of vertical displacements in the model including geogrids (top) and with no geogrid (bottom). Axial forces on the geogrids are also shown on the top figure.
The HCItasca offices in Africa and Chile have moved in the last few months. Please note the new contact information for each office.
Itasca Africa (PTY) LTD
16 Orange Street
Sunnyside, Auckland Park
2092 South Africa
phone: (+27-11) 482-8840
or (+27-11) 482-8841
itasca@itasca.co.za
The above is the physical address of the office; the mailing address is:
P.O. Box 291375
Melville 2109
South Africa
Itasca S.A.
Luis Carrera 1263, Of. 402
Vitacura, Santiago de Chile
Chile
phone/fax: (+ 56-2) 436-0257
consultores@itasca.cl
Visit the
conference site
Sea to Sky Geotechnique 2006
HCItasca will be well-represented at the upcoming Sea to Sky Geotechnique 2006, the 59th Canadian Geotechnical Conference and the 7th Joint CGS/IAH-CNC Groundwater Specialty Conference. The Conference will be held in Vancouver, British Columbia, Canada and runs from October 1-4, 2006. Four articles by authors from HCI (John Mahoney, Roger Howell, Lee Atkinson, Vladimir Ugorets, and Dirk Sutphin) and one by an author from Itasca Consulting Group, Inc. (Andrew Corkum) will be included in the proceedings. In addition, HCItasca will have a booth in the exhibit hall. Please stop by if you are planning to attend the conference.
Visit the
conference site
Geomechanics Colloquium
The Technical University of Freiberg will host a Geomechanics Colloquium on November 17, 2006. The keynote lecture, entitled "Numerical Experiments in Geotechnical Engineering: Some Applications in Nuclear Waste Isolation," will be presented by Charles Fairhurst and Branko Damjanac of Itasca Consulting Group, Inc. Presentations will also be given by Prof. Heinz Konietzky and Dr. Lothar te Kamp of Itasca Consultants GmbH, in cooperation with other scientists/engineers. There will be a one day Itasca-Seminar preceding the colloquium the afternoon of November 16, organized by Itasca Consultants GmbH Germany and Heinz Konietzky, who also serves as the Chair of Rock Mechanics at the Technical University of Freiberg.
Visit the
conference site
IAMG '06
Itasca Consultants, S.A.S. will be represented at the beginning of September at the IAMG 2006 Annual Conference on "Quantitative Geology from Multiple Sources." The conference will be held in Liège, Belgium and runs from September 3-8, 2006. Céline Bourdeau will present her work about "Impact of groundwater flow on the seismic triggering of landslides: a numerical analysis" on Monday, September 4, 2006, room S94.
Recent Conference Participation
In June Itasca Consultants, S.A.S. participated in two French scientific meetings. Céline Bourdeau presented her work on the "Analysis of Geogrids' Efficiency to Prevent the Local Collapse of a Road" at the "Les 6e rencontres Géosynthétiques" in Montpellier (see Consulting above). At the end of June, Itasca Consultants, S.A.S had a booth during the "Journées Nationales de Géotechnique et de Géologie de l'ingénieur," which provided the opportunity to meet current clients and to present its activities to future customers.
IAEA trainees with
instructors Roger Hart and Yanhui Han
Participants from ten countries attended the International Atomic Energy Agency (IAEA) Training Course on Numerical Modeling of Subsurface Processes related to nuclear waste isolation. The course was held at the offices of Itasca Consulting Group, Inc. in Minneapolis, during the week of August 7-11. The training focused on the use and application of FLAC for numerical analysis in repository engineering and design. The course is intended to help IAEA member countries gain knowledge of the application of numerical codes for mechanical, groundwater, thermal and coupled analyses pertaining to nuclear waste isolation. The course notes are available in PowerPoint format to anyone interested.
About
Windows
Remote
DesktopRecent changes to the security key logic utilized by current and pre-release versions of FLAC3D, PFC2D, and PFC3D have made it possible to use these codes with Windows Remote Desktop. If you would like use this built-in feature of Windows XP, please visit the download pages for FLAC3D 3.0, FLAC3D 3.1, PFC2D 3.0, PFC2D 4.0, PFC3D 3.0, and PFC3D 4.0 to obtain the latest updates to these codes that contain the functionality. Please note that these code updates also require an upgrade to the security key driver. The upgrade installation and instructions on its use are also available from these pages.
Publications since July 6, 2006:
Blümling, P., and H. Konietzky. (2004) "Calibration and Verification of a Constitutive Law for Opalinus Clay - Results from Laboratory and in-Situ Tests," in 2nd Colloquium of Rock Mechanics - Theory and Practice (Mitteilungen Für Ingenieurgeologie und Geomechanik der TU Wien), pp. 88-95.
Christianson, M. C., M. P. Board and D. B. Rigby. (2006) "UDEC Simulation of Triaxial Testing of Lithophysal Tuff," in Golden Rocks 2006 — 50 Years of Rock Mechanics, Colorado School of Mines, June 2006 (Proceedings of the 41st U.S. Rock Mechanics Symposium). Paper No. 06-968, D. P. Yale, et al., Eds. ARMA.
Detournay, C., and B. Wu. (2006) "Semi-Analytical Models for Predicting the Amount and Rate of Sand Production," in Multiphysics Coupling and Long Term Behaviour in Rock Mechanics (Proceedings of ISRM Eurock 2006, Liège, Belgium, May 2006), pp. 373-380, A. Van Cotthem et al., Ed. London: Taylor & Francis Group.
Furtney, J. K. (2006) Some Aspects of Fluid Flow in the Earth's Crust. Ph.D. Thesis, Darwin College, Department of Earth Sciences, BP Institute, University of Cambridge, April.
Furtney, J. K., and A. W. Woods. (2006) "Limitations in Qualitative and Quantitative Analysis of Time-Lapse Data Due to Fluid Flow Uncertainties," J. Geophys. Eng., 3, 194-205.
Gaffney, E. S., and B. Damjanac. (2006) "Localization of Volcanic Activity: Topographic Effects on Dike Propagation, Eruption and Conduit Formation," Geophys. Res. Letts., 33, L14313, doi:10.1029/2006GL026852.
Shimizu, Y. (2006) "Three-Dimensional Simulation Using Fixed Coarse-Grid Thermal-Fluid Scheme and Conduction Heat Transfer Scheme in Distinct Element Method," Powder Tech., 165, 140-152.
Under Development