CATCH BENCH DESIGN IN JOINTED ROCK MASSES

by Jim Mathis

24 - 25 September 2008 Vancouver Canada

Course Presenters Schedule General information

Jim Mathis

Originally from Nevada, USA, James Mathis spent most of his younger years wandering the mountains hunting, fishing, trapping, and licking rocks.  He graduated from the University of Nevada – Reno with a BS in mining engineering in 1981.  Subsequent to graduation, he worked for Call and Nicholas in Tucson, AZ where he developed his interest in statistical rock mechanics.  He obtained his Ph.D. in rock mechanics from the University of Lulea in Sweden in 1988.

From 1990 to 1995 he was a senior geotechnical engineer for Steffen Robertson and Kirsten and became the North American rock mechanics engineer for the company.  In 1995 he went independent, starting his own company, Ursa Engineering.  This changed names to become Zostrich Geotechnical, and continues under that name to this date.

Dr. Mathis’ work includes the development of statistical data collection and modelling techniques for discontinuities in rock masses.  This includes description of small scale joints incorporated in rock fabric to larger scale faults and shear zones.  This work been expanded to incorporate statistical analyses of the varying common existing, as well as unique, failure modes in rock masses and has been implemented by Dr. Mathis in open pit and underground rock mechanics designs for over 20 years.

The present design process for open pit mines utilized by the author at present incorporates:

1. statistically describing bench failure modes, incorporating strengths and rock fabric, to accurately determine bench face angles;
2. determine safe, effective catch bench widths and appropriate profiles;
3. utilizing statistical inference, as well as discrete features, determine interramp and overall pit slopes;

The most notable applications of this process have been at BHP Billiton Diamond's Ekati mine where all of the pits have been designed using this methodology.