Groundworks June 2007 HCItasca eNewsletter

HCItasca has always endeavored to provide local expertise combined with global perspective. With the opening of offices in China (late 2004), Japan (April 2006), Houston (May 2007) and now Australia (see HCItasca World below), our expanded reach means we can provide more face-to-face contact with clients while also delivering the breadth of experience that comes from having a truly international pool of engineering talent upon which to draw.

—John Markham

Downstream side of Bin El Ouidane Dam (Source: INGEMA)

Above: FLAC3D model showing pore pressures at the end of the first reservoir filling (January 1956)

Left: Agreement is seen between the measured and modeled pendulum displacements.

To improve monitoring of the Bin El Ouidane dam, built in 1952, Itasca Consultants SAS (Ecully, France) was asked by INGEMA to conduct a FLAC3D analysis of the behavior of the "dam + rock" system with respect to seasonal temperature variations and water level changes in the reservoir. The dam was constructed with independent cantilevers, later grouted to make the arch monolithic. For each set of model parameters (water level in the reservoir and air temperature) corresponding to one particular moment in time, new pore pressures and heat fluxes between the dam and the air, on one hand, and the dam and the water, on the other, were calculated. These phenomena affect the mechanical behavior of the dam, as shown in the graph below, which depicts radial and tangential pendulum displacements from September 1998 to August 2004. The resulting thermo-hydromechanical model was calibrated using measurements available since the dam's construction and is capable of predicting its future behavior. Future normal and abnormal behavior of the dam can be determined by comparing the simulated motions and measured ones.

Current Versions updated since March 16, 2007

PFC 4.0 Feature Highlight
The smooth joint contact model, one of the new features in PFC2D and PFC3D 4.0, represents a breakthrough in DEM modeling. Smooth joints simulate the behavior of a through-going interface regardless of particle orientation. Using smooth joints, PFC becomes a DEM code that can model the behavior of jointed material. A descriptive overview of this new feature in PFC, as well as preliminary documentation, is available now.

7/193A Lennox Street
Richmond Victoria 3121
Australia
http://www.itasca.com.au/

HCItasca is pleased to announce the formation of Itasca Australia Pty Ltd. The new office will bring the advanced geomechanics consulting and software services of HCItasca to the Australian mining and civil industries. Located in Melbourne, the office officially begins operations July 1 and will be staffed by David Sainsbury, Bre-Anne Sainsbury, and David Wines. Specific areas of expertise include:

underground mine design and rock mechanics
analysis of open pit slope stability
mine backfill geomechanics
tunneling excavation and ground support design
analysis and design of large underground excavations

HCItasca extends its appreciation and thanks for the many years of service that M.A. Coulthard and Associates has provided as the Australasian Itasca code agent. Beginning July 1, Itasca Australia will be the sole distributor and support provider for the Itasca suite of codes within Australia, New Zealand, Indonesia and Papua New Guinea. For all general enquiries, please email itasca@itasca.com.au; software support questions should be sent to software@itasca.com.au. For more information on Itasca Australia's consulting and software services, please visit http://www.itasca.com.au/.

Mott MacDonald, Itasca's software sales agent in the United Kingdom, will host a three-day FLAC Practical Applications training course July 25-27 at its office in Croydon, England. For information on this and other training opportunities around the world, please refer to the training schedule.

The Depot Minneapolis
A Renaissance Hotel
225 3rd Avenue South
Minneapolis, MN 55401

Deadline Extension!
By popular demand, the abstract submission deadline for the 2008 FLAC/DEM conference has been extended to July 1, 2007.

Venue Announced
We are also pleased to announce that the venue for the conference has been selected. The Depot Minneapolis, A Renaissance Hotel, located just a block away from the offices of Itasca Consulting Group, Inc., will serve as the main location for the symposium proceedings. Participants are responsible for their own hotel accommodations. A block of rooms at The Depot Hotel has been reserved for Symposium attendees at a special rate. Rooms are limited and reservations must be made by July 24, 2008. Once this date has passed or the room block has filled, availability and rates are subject to change. To reserve a room, call 1-866-211-4611 (reference "Itasca Consulting" when making your reservations).

Registration Open
Registration forms are available at the Symposium web site. These forms can be filled out on-screen using Acrobat Reader, then simply printed, signed, and returned with payment.

enlarge

When generating a contour plot of a zone related quantity in FLAC3D (e.g., stress or strain), FLAC3D first sends this quantity to the gridpoints and then generates contours from these gridpoint values on the zone faces. If your model contains an excavation consisting of null zones, it is often desirable to visualize these zone related quantities on the excavation faces from an observation point outside the excavation as in the adjacent diagram. Because the null zones do not contain any stress information, it is impossible to generate a stress plot on the surfaces of the null zones directly using a command such as PLOT CONT SZZ RANGE GROUP MYNULLZONES. With FISH, these zone related quantities can be sent to a gridpoint extra location and contoured (example code is available for download: groundworks0706.dat).

Literature by HCItasca personnel recently published or acquired in the HCItasca library.

DeGagné, D. O., and S. D. McKinnon. "The Influence of Cave Mass Properties on Discrete Sublevel Cave Models," in Golden Rocks 2006 — 50 Years of Rock Mechanics, Colorado School of Mines, June 2006 (41st U.S. Rock Mechanics Symposium). Paper No. 06-1148, S. Yale et al., Eds. ARMA, 2006.

Gómez, P., M. Díaz and L. Lorig. "Stability Analysis of Waste Dumps at Chuquicamata Mine, Chile," Felsbau, 20(6), 61-68 (2002).

Hausdorf, A., Heinrich, F., Konietzky, H., Mocka, N. "Numerische Untersuchungen zur Stabilität geschichteter und geankerter Kammerfirsten im Kalibergbau / Numerical studies on the stability of bedded and anchored roofs of the rooms in potash mining", Kali und Steinsalz, 1(2007)24, p. 20-25.

Mas Ivars D., Pierce M., Potyondy D. O. and Cundall P.A. (2007). "A new modelling approach for the study of deformation, yield and failure of jointed rock masses", in Bergmekanikdag 2007, Stockholm, Sweden, pp. 33-41. SveBeFo 2007.

Pierce M., Potyondy D. O., Cundall P.A. and Mas Ivars D.(2007). "A synthetic rock mass model for jointed rock", in Rock Mechanics. Meeting Society's Challenges and Demands (Proceedings of the 1st Canada-US Rock Mechanics Symposium, Vancouver, Canada, 27-31 May 2007), pp. 341-349. E. Eberhardt, D. Stead, T. Morrison, Eds. Taylor & Francis, 2007

Revell, M. B., and D. P. Sainsbury. "Advancing Paste Fill Bulkhead Design Using Numerical Modeling," in Minefill 2007 — Innovation and Experience (Proceedings of the 9th International Symposium on Mining with Backfill, Montreal, May 2007). CD Proceedings, Paper No. 2473. Montreal: CIM, 2007.

Revell, M. B., and D. P. Sainsbury."Paste Bulkhead Failures," in Minefill 2007 — Innovation and Experience (Proceedings of the 9th International Symposium on Mining with Backfill, Montreal, May 2007). CD Proceedings, Paper No. 2472. Montreal: CIM, 2007.

Sainsbury, D. P., and R. Urie. "Stability Analysis of Horizontal and Vertical Paste Fill Exposures at the Raleigh Mine,", in Minefill 2007 — Innovation and Experience (Proceedings of the 9th International Symposium on Mining with Backfill, Montreal, May 2007). CD Proceedings, Paper No. 2527. Montreal: CIM, 2007.

Schlegel, R., Konietzky, H. & Will, J. "Optimization and Sensitivity Analysis in Mining and Geotechnical Engineering using Numerical Approaches", Buletin Resurse Minerale, Nr. 2, 2006, P. 47-54.